Cisco EPC3925 stops working when a wired PC is starting

[doom_laur]

Hello!

I have an EuroDOCSIS 3.0 cable modem from UPC Romania. It's a Cisco EPC3925, wireless modem.

My problem is that most of the time (like 80% of the time) when someone is starting or closing a PC that is connected using a wire, the whole internet crashes (wired PCs get a ! sign and the internet stops working and wireless PCs are getting disconnected completely from the network being unable to reconnect). This is solved by restarting the modem (unplugging/replugging it) or waiting for it to reconnect. I want to mention that during this process the modem lights show that everything is ok and nothing special happens.

First of all I called UPC technical support and the man there said that I should try to disable the firewall from the modem (which I had disabled already), if it won't help then to try to reset the modem to the factory settings (as I was thinking to do - because I configured the settings as I wished) and if this won't help then calling them back to change the modem.

I tried to reset to the factory settings and that didn't help at all after running tests over one week. After that I called UPC and they said that the modem is for sure the problem, they sent a technician (today) who also said that the modem is the problem. Ok ok, the technician replaced it and everything seemed to be good.

30 minutes ago my father started his PC and what should I see? Bam, internet crashing. 5 minutes ago i closed as well my PC and what should I see? The internet crashing again.

Please help me to solve this problem, I am desperate. For some personal reasons I also can't change the provider and I don't want to spend the rest of my life telling my father when I'm closing my PC and he telling me the same.

Thank you in advance!

[Fred Garvin]

Has more than one computer ever been able to get online at the same time?
Look at the back of the modem, how many LAN ports are there?

[doom_laur]

Yes, if I'm not wrong I connected up to 7 devices (computers, tablets and smartphones) from which 2 of the computers were wired.

As most of the wireless modems and routers have, my EPC3925 has 4 ports at the back for wired connections.

Maybe this will help, here is the manual from the modem: http://manual.upc.ro/pdf/epc_3925.pdf

Thanks for the response!

[Fred Garvin]

I would probably reset the modem/router back to its defaults and start everything from scratch using the manual.

Go into your router's setup page and make sure you don't have a limited # of DHCP Users set (P34 in the manual). Set the # to 50.

Make sure each computer, printer, etc. is set to automatically obtain an IP address and not set to a static IP. You can use steps 1-5 in this guide to check.

Go into Control Panel> Network Connections and right click on your Local Area Connection or Wireless Connection. Go to Advanced. Make sure "Allow other users to connect though this connection" is Not checked.

Right click on your network connection and go to Properties, then the Configure button. Select the Power management tab. Make sure the box is Not checked for "Allow the computer to turn off this device..." Check these settings on each PC.

Power off ALL devices that connect to the router then turn on one at a time and see if they get online before turning on a 2nd computer.

[doom_laur]

I already tried to reset everything to the default settings using a paper clip at my old modem and it did not help. Another reason why I wouldn't prefer to do this again is because I would disturb my whole family again with that, and it's something that I would prefer to not do since I tested it already.

About the maximum number of DHCP users, by default it is set to 119 (don't ask me why it's 2 in the manual) so that can't be the problem.

About the other steps, I always had my IP settings fully automatic. "Allow other users to connect though this connection" was disabled already. "Allow the computer to turn off this device..." - I disabled that but it did not help.
Thank you again for your kindness.

P.S.: I'm solving the easy problems 99% of the time by myself, and I'm only asking experts about harder problems. Unfortunately, usually experts can't help either Let's hope that won't be the case this time.

[Fred Garvin]

No problem, I understand about not wanting to reset again. Have you checked the other computers to make sure they have Internet Connection Sharing disabled? I'm just wondering if someone else setup their computers wrong and are connecting through ICS.

The other thing I would try is - use one computer at a time, check its IP address then power on another computer. IP conflicts are the only other thing that come to mind. I'll ask some of the others to take a look at this thread.

[Old Rich]

Please do this on two machines . . one connected by itself and a second pc connected

with the pc connected to the router, Click on Start . . Run . . type CMD

At the > prompt type type the following command: IPCONFIG /ALL


Note that there is a space before the /ALL, but there is NOT a space after the / in the following command.

Right click in the command window and choose Select All, then hit Enter. Come back here and Paste the results in a message.

[doom_laur]

From my desktop (wired PC):

Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation.  All rights reserved.

C:\Users\doom_laur>ipconfig /all

Windows IP Configuration

   Host Name . . . . . . . . . . . . : doom-laur-dsk
   Primary Dns Suffix  . . . . . . . :
   Node Type . . . . . . . . . . . . : Hybrid
   IP Routing Enabled. . . . . . . . : No
   WINS Proxy Enabled. . . . . . . . : No

Ethernet adapter Local Area Connection 3:

   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Bigfoot Networks Killer Ethernet Controll
er
   Physical Address. . . . . . . . . : 00-19-03-03-D8-15
   DHCP Enabled. . . . . . . . . . . : Yes
   Autoconfiguration Enabled . . . . : Yes
   Link-local IPv6 Address . . . . . : fe80::1999:185a:3267:8e55%14(Preferred)
   IPv4 Address. . . . . . . . . . . : 192.168.1.13(Preferred)
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Lease Obtained. . . . . . . . . . : 8 martie 2012 12:25:11
   Lease Expires . . . . . . . . . . : 9 martie 2012 12:25:10
   Default Gateway . . . . . . . . . : 192.168.1.1
   DHCP Server . . . . . . . . . . . : 192.168.1.1
   DHCPv6 IAID . . . . . . . . . . . : 369105155
   DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-16-18-94-36-8C-89-A5-32-E6-1E

   DNS Servers . . . . . . . . . . . : 95.77.94.88
                                       78.96.7.88
   NetBIOS over Tcpip. . . . . . . . : Enabled

Tunnel adapter isatap.{2FB04D28-577D-4D22-830A-12A3082940EB}:

   Media State . . . . . . . . . . . : Media disconnected
   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Microsoft ISATAP Adapter
   Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
   DHCP Enabled. . . . . . . . . . . : No
   Autoconfiguration Enabled . . . . : Yes

Tunnel adapter Teredo Tunneling Pseudo-Interface:

   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Teredo Tunneling Pseudo-Interface
   Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
   DHCP Enabled. . . . . . . . . . . : No
   Autoconfiguration Enabled . . . . : Yes
   IPv6 Address. . . . . . . . . . . : 2001:0:5ef5:79fb:3cf2:9:3f57:fef2(Preferr
ed)
   Link-local IPv6 Address . . . . . : fe80::3cf2:9:3f57:fef2%11(Preferred)
   Default Gateway . . . . . . . . . : ::
   NetBIOS over Tcpip. . . . . . . . : Disabled

C:\Users\doom_laur>

From my laptop (wireless PC):

Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation.  All rights reserved.

C:\Users\doom_laur>ipconfig /all

Windows IP Configuration

   Host Name . . . . . . . . . . . . : doom-laur-lap
   Primary Dns Suffix  . . . . . . . :
   Node Type . . . . . . . . . . . . : Hybrid
   IP Routing Enabled. . . . . . . . : No
   WINS Proxy Enabled. . . . . . . . : No

Ethernet adapter Local Area Connection:

   Media State . . . . . . . . . . . : Media disconnected
   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Marvell Yukon 88E8059 Family PCI-E Gigabi
t Ethernet Controller
   Physical Address. . . . . . . . . : 00-24-54-81-B1-E3
   DHCP Enabled. . . . . . . . . . . : Yes
   Autoconfiguration Enabled . . . . : Yes

Wireless LAN adapter Wireless Network Connection:

   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Atheros AR9285 Wireless Network Adapter
   Physical Address. . . . . . . . . : F0-7B-CB-5F-34-90
   DHCP Enabled. . . . . . . . . . . : Yes
   Autoconfiguration Enabled . . . . : Yes
   Link-local IPv6 Address . . . . . : fe80::40da:b86c:29cc:3fe3%30(Preferred)
   IPv4 Address. . . . . . . . . . . : 192.168.1.14(Preferred)
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Lease Obtained. . . . . . . . . . : 8 martie 2012 12:25:44
   Lease Expires . . . . . . . . . . : 9 martie 2012 12:25:47
   Default Gateway . . . . . . . . . : 192.168.1.1
   DHCP Server . . . . . . . . . . . : 192.168.1.1
   DHCPv6 IAID . . . . . . . . . . . : 401636299
   DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-13-02-B1-A5-00-24-54-39-E8-3B

   DNS Servers . . . . . . . . . . . : 95.77.94.88
                                       78.96.7.88
   NetBIOS over Tcpip. . . . . . . . : Enabled

Tunnel adapter isatap.{5A573C52-3497-4A61-94A3-D0D267BC975B}:

   Media State . . . . . . . . . . . : Media disconnected
   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Microsoft ISATAP Adapter #2
   Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
   DHCP Enabled. . . . . . . . . . . : No
   Autoconfiguration Enabled . . . . : Yes

Tunnel adapter Local Area Connection* 20:

   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Teredo Tunneling Pseudo-Interface
   Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
   DHCP Enabled. . . . . . . . . . . : No
   Autoconfiguration Enabled . . . . : Yes
   IPv6 Address. . . . . . . . . . . : 2001:0:5ef5:79fb:24a9:19e5:3f57:fef1(Pref
erred)
   Link-local IPv6 Address . . . . . : fe80::24a9:19e5:3f57:fef1%34(Preferred)
   Default Gateway . . . . . . . . . : ::
   NetBIOS over Tcpip. . . . . . . . : Disabled

C:\Users\doom_laur>

P.S.: I forgot to mention that I have a dual boot at my laptop with Windows 7 and Ubuntu 11.10 and I have the same problem like at the other PCs, but of course it stops working only when I'm closing a wired PC, as I described above.

[Wand3r3r]

Might try assigning these two pcs static ips and then see if you have the same issue.

[TheCyberMan]

Updating the firmware for the modem may help.

[doom_laur]

Originally Posted by Wand3r3r

Might try assigning these two pcs static ips and then see if you have the same issue.

If you look in the manual I posted above at the same page as the settings with "Maximum Number of DHCP Users", you'll see a button with "Pre-assigned DHCP IP Adresses". There the modem adds automatically all the new devices to the list and creates for them a static IP. You can also do that manually from there - but that's not important, you got my idea

Originally Posted by TheCyberMan

Updating the firmware for the modem may help.

I don't think that it's possible. It has custom firmware from UPC Romania and I think that only UPC can upgrade it. The name of the software revision is: EPC3925-ESIP-12-v302r125532-110616c_upc <-- which tells me that it has custom firmware.

[Wand3r3r]

You missed my point. Eliminate dhcp from the mix by manually assigning static ips to the pcs not in the dhcp scope. I would suggest you turn off the dhcp feature in the router while testing.

[TheCyberMan]

It may well be worth contacting UPC Romania and asking if a firmware update is available it could help.

[doom_laur]

Originally Posted by TheCyberMan

It may well be worth contacting UPC Romania and asking if a firmware update is available it could help.

I called them and asked them and the man from the support team asked me (for the first time since I'm calling them) to activate the Remote Management feature of the modem - something that noone from support asked me before - and he looked at my setting and said that I configured it very good (like disabling the firewall). Then he said that he changed a setting and it shouldn't desynchronise anymore, and if it will I should call them back to make some tests at their network in my area.

Originally Posted by Wand3r3r

You missed my point. Eliminate dhcp from the mix by manually assigning static ips to the pcs not in the dhcp scope. I would suggest you turn off the dhcp feature in the router while testing.

Sorry for misunderstanding, I will try that after I will see if the problem will be solved with calling UPC. Thank you

[TheCyberMan]

Yes if the issues re-occur contact UPC Romania again as they can check the network their end.

Hopefully your issues wont re-occur.

Can i ask whether the issue of disconnection occurs when a specific device connects to the network or is it a random thing it happens with the varouis different computers?

[doom_laur]

Well it happens both with mine and my father's desktop, and one time I even connected the laptop with a wire to my modem and the internet stopped working, so it's not caused by the pc.

I want to mention two more things that may help in the case that the problem won't be fixed: when the internet stops working the modem lights indicate normal activity like nothing in happening and UPC doesn't see any problem in their systems and also, when it stops working, I have no pulse at the landline (it's a VOIP telephone).

[doom_laur]

One more thing, the internet seems to crash only when I have at least one device (computer, smartphone or tablet) connected already, and when I'm connecting the second one it stops working usually. It happened very rarely, or maybe it never happened (I can't remember) when I had only one device connected at one time.

[Fred Garvin]

Have you tried turning on additional computers besides the 2 you posted the Ipconfigs for, or turned off one of those 2? I've come across several ISP modems/routers where they use custom firmware and it's just plain stupid the way they're configured. Sometimes you're better off using only their modem and getting your own wireless router. Also, one of the best features of a router is its firewall capability. That's not something I'd turn off.

[doom_laur]

Well I will try to do more things after I'll see that UPC can't help me. But until then I'll answer your other questions.

I need a router/modem with integrated router because I have more devices in my apartment and I need to connect more devices. Besides that I don't need any security and so on. Since I'm not a person who's starting the PC 15 minutes per day and watching the online newspaper, I need my own settings.

I'm a gamer and I don't want my modem to block my ports and so on, nor I want to configure the ports for every game. Because of that I'm disabling as much security as possible (except the wireless security of course - which I keep at maximum) including firewall, enabling UPnP and putting my desktop PC into DMZ. I have BitDefender Total Security 2012 and I'm using its firewall which is great, compared to the firewall on any modem or router which just blocks everything you're setting it to block.

Hardware firewalls don't have smart firewalls, like: I want to block the access of a hacker or spy to my PC, but I don't want to block my games. Nope, it'll just block everything. I'm trying to disable as much security features as possible. Even UPC recommends me to do so, lol, without knowing that I'm doing that since years. With the default settings for example I can't even connect to my TeamSpeak 3 server (I'm hosting it when I need it on my own PC) or connect to my own website which I'm creating and hosting on my PC for different situation.

In short, I want a modem or router to let me connect more devices, not to add me more security which I don't need.

[TheCyberMan]

Hi understand you are waiting for UPC but you can try things in the meantime.

You missed my point. Eliminate dhcp from the mix by manually assigning static ips to the pcs not in the dhcp scope. I would suggest you turn off the dhcp feature in the router while testing.

Please don't overlook Wand3r3r's advice.

1. Please try and connect one device at a time and monitor for disconnections over a period of time. Please do not connect a second device. It may be time consuming but it could help in some way to identifying a problem. Did any one device not disconnect or did they all stay connected.

2. Connect a smartphone and a tablet together do you suffer disconection when these two are connected at the same time?

3.If the smartphone and tablet stay connected add one of the pc's into the network make a note of which pc you are adding in. Do all three stay connected?

If all three stay connected add another pc or laptop to the network again make a note of which one you are adding in keep doing that until you have a disconnection.

If when all three are connected it disconnects make a note that the pc disconnected and remove that from network and try another again make a note of which one.

The point local firewalls on pc's can detect new devices on the network and can see them as an intruder usaually a pop message comes up but depending on configuration some may block them from accessing the network and internet and blanket the block network wide for some reason.

I am not saying this is what is happening here just a shot in the dark.

I would not advise disabling your security features hackers and spy's do not advertise themselves they like to blend in or masquerade as a genuine service such as svchost to try and hoodwink your security.

I'm trying to disable as much security features as possible. Even UPC recommends me to do so

Your isp has given you bad advice if they recommended that and is poor service.
If my isp said that to me i would be saying bye bye and looking for a new provider.

If you are hosting a website you would need to forward port 80 thru the router to the pc's ip address hosting the website and for Teamspeak 3 server forward the ports required to it's ip address also but that will be for another thread.