Probably a non-standard issue here, but I can't figure out what's going on with my networking. Hope someone on this thread has seen some similar behavior...
It sounds like a network conflict or UPnP flood. Is your router completely up to date? I have the same one and I haven't noticed anything similar. Wake on Lan makes it freak out as well sometimes, you can disable that on the motherboard.
Thanks for the hints! My router is running the latest WRT-Merlin as of yesterday, but looks like they have put a new build out today. I will try that just in case.
I thought I would see something in the router logs, but nope. No UPnP problems, no conflicts whatsoever. Also pretty sure I have Wake-on-Lan disabled on the board but I will check again.