This is a weird one. My MacBook will just stop communicating on my network. It shows that it is connected to WiFi, and if I reboot it it will load a webpage for the first few seconds after I login, but then it just stops all network communication - even though it still shows connected to WiFi. Nothing else on my network is impacted. I can’t ping in or out. I reinstalled macOS and it worked, for about 4 days, then stopped working again.
Anyone seen this before?
Most likely hardware issue. You might try running a live Linux USB to see if it still happens in there just to rule out any funky Apple software issues. But the refresh of macOS seems enough there.
Unfortunately it’s not going to be easy if you don’t have AppleCare. Apple solders everything to the main board so it’s not like you can just remove the WiFi card like nearly every other computer out there.