wickedfork,
I'm hoping this will be a quick fix (found at:
http://www.dslreports.com/faq/sbc/3.1_Speedstream_5100)
Why doesn't my Router work with the 5100
Routers with the default IP of 192.168.0.1 (example Netgear) conflict with the 5100B default of 192.168.0.1. The administrative access IP for the router has to be changed, since the 5100B's cannot be changed.
How to setup the 5100b or 4100 with a router/hub
If you want to network your connection with the 5100b you will need a router. The 5100b hands out only one LAN IP address (and does NAT) so a hub will not work. There are two methods you can use to network the 5100b. While initially, The first was the recommended version, as time went on, and users and support got used to the idea of PPPoE on the modem, the second approach has become the preferred method.
Method 1 (Single NAT) -
1: With your computer plugged directly into the modem bridge the modem using the FAQ entitled How can I put the 5100b in bridge mode?
2: Plug the router in between the modem and your computer.
3: Set your router up for PPPoE and put in your full e-mail address and password. If it asks for an IP address or anything like that you can just leave those fields blank.
4: You should now be online, given the possible need to restart your devices.
Method 2 (Double NAT) -
1: With your computer plugged directly into the modem follow the FAQ entitled How do I setup the 5100b to connect to the internet?
2: Plug the router in between the modem and your computer.
3: If your router has an IP address of 192.168.0.1 then you should change it to something else like 192.168.2.1. 192.168.1.1 will work, but if it assigns 192.168.1.64 to a device, it won't route correctly, since the 5100b will assign the router 192.168.1.64 on its WAN side.
4: Setup your router for DHCP on the WAN side, or set it statically to 192.168.1.64 with a subnet mask of 255.255.0.0
5: You should now be online, given the possible need to restart your devices.
Note: Although this Method 2 is termed "Double NAT", the modem is acting as though it is in DMZ mode and passing all port traffic through to the router. There can be a connection drop or lock up problem with this method, if too many TCP connections (sessions) are opened by some gaming or P2P software. Apparently the modem's NAT table memory overflows when this happens.
I'm thinking you simply need to change the router's network address to something other than 192.168.0.X as this conflicts with your DSL modem's addressing scheme. This would explain why things stopped working after you factory reset your old router. It was likely custom configured to a different IP network address that didn't conflict with that of your DSL modem.
Hope this works!
- John