Small business server/network madness

Hello all.

I’m hoping you can give me some advice on the cluster of problem im having with my server. Firstly I am not an IT expert in much of anything. I’m mostly self taught over the years and id like to think I’m a quick learner. So lets get into it.

Here’s the situation. I’m wearing my “IT” guy hat today.
Ive got an aging HP proliant ML350 G6 running 2 Xeon CPUs @2.13GHz with a whopping 8GB of memory.
Purchased new in ~2009-10 ish
Network teaming is enabled and has been for years so theoretically 2.0Gbps local bandwidth with both Cat6 cables connected to switch.
Running Windows server 2008r2
Currently running raid 1 setup for C disk using 2 500GB Samsung SSDs and Raid 5 setup with 3 Samsung 500GB SSDs
This server has 2 jobs, function as a basic file server (document sharing etc) and run this businesses management software. For it to work all workstations have to copy an .exe shortcut from the shared drive onto their desktops and launch from there.

Network consists of All Cat6 cabling, 48 port netgear smart switch. Approximately 20 workstations, 2 business related machines that need basic internet access and server access, 4 network large printers and about 20 VOIP phones. ATT combo modem/router on an incredible 50mbps bandwidth (VDSL). The workstations have been slowly transitioned over to windows 10 from 7.

Problems that Im having:
For several years now RDP randomly refuses to work even if I was just able to login a few moments prior. Sometimes I can remote into a workstation and then remote into the server. Frequent messages saying “Unable to allocate more memory” or similar. The biggest issue has been simply not being able to access the shared drive on a weekly and sometimes daily basis that requires rebooting the server and or switch. When I look at the event viewer on the server its constantly getting “Fatal error 70” messages multiple times per hour. Ive tried to dive down the rabbit but there are too many events to keep up with. Is there a common cause to a lot of these events? And of course if we cant access the shared drive we cant run the business software to actually function.

Ive been interested in getting a new server but there are so many choices. I can always add more ram but that’s not going fix these other problems.

A new fun discovery while accessing the modem/router is that my server is listed as having ip address that ends in “.7”, ive always used a static “.9” assigned on the NIC and on the router. The server pings correctly for “.9”. I have no idea why the router has the “.7” listed.

I would also love some advice on server replacement vs switch recommendations if that is what is necessary. Im not able to upgrade the internet bandwidth due to poor property management denying my requests. They want us to move elsewhere but thats not really an option in the foreseeable future.

Thanks, let me know what you think.