Question Computer loses Ethernet connection some time after being powered on (among other issues)

jmpt14

Commendable
Oct 14, 2021
15
0
1,510
So I've been given an old work PC (an HP 290 G1 Microtower), and I've been using it as a makeshift NAS. However, recently it's been giving me trouble.
Earlier this week I was transferring files over it, when suddenly it stopped being connected to the network. Now, when I say it wasn't connected, I mean the Ethernet port was dead. Windows told me that "no network cards were detected, check drivers" (for reference, the Ethernet port is on the motherboard). I did everything I could; checked if the cable or the router were busted (they were fine), installing HP's network drivers from their site, reinstalling Windows all together - no luck.
I gave up and tried again the next day. Lo and behold, it was connected... for like 5 minutes, and then the problem resurfaced. I left it completely unplugged yesterday, and today it maintained a connection for almost 30 minutes.

What can I do to fix this?

Other notes:
- Yesterday, it gave me CMOS checksum problems. I put in a new CMOS and updated the BIOS just in case. No more CMOS/BIOS complaints, network problems persist.
- Just this afternoon, one of the USB ports died on me, and I only know this because it was the port where my keyboard was plugged in, ergo; the PC wouldn't detect a keyboard and warn me. Keyboard works, the other ports work, but given that both the USB port and the Ethernet port are bugging out, I fear the I/O might die out completely.

>inb4 get a new motherboard/power supply
Can't, they're specific to this chassis+mobo combination. Business PCs, am I right?
>inb4 get a network card
The only avaliable PCIe slot is currently occupied by a graphics card. Unless the inbuilt Ethernet port dies for good, I'd like to keep it.