Networking ceases after a few minutes

I have the second revision of the PS3 which was serviced by Sony because of some type of overheating issue (this was a few years ago, so I don’t remember, but they replaced the main board). I wasn’t able to test the machine after I got it back due to moving. Once I finally did get the chance, I found that both wireless and wired networking would stop working after a few minutes of the PS3 being powered on. I’d know this because I would have a constant ping going to the PS3 and it would respond, until it was powered on for a few minutes.

Is the NIC a separate board that can be replaced? Or is the network controller on the main board itself and would require another swap (of course Sony doesn’t service these anymore).