Ok
My PC has this issue.
The GFs PC is fine. Ruling out a router issue.
I have tried
replacing network cable, drivers, fresh install, factory reset of router, multiple ports on router
nothing seems to fix it. Im guessing faulty on board NIC ?
its a ASUS z170 motherboard, probably still within warranty, but tbh i ****ing hate this POS i wish i never got it. I bent a few CPU pins though when i installed the 6700k about 6 months ago. So i doubt ill be doing the warranty route.
Before i buy either a new Mobo... sigh, or a cheap PCIE network card (sadly more likely) are there any more tests i can do or try ?