I just recently upgraded my router from 2860vac to 2927ac so I can increase my download bandwidth so it’s more than 400MB but I’ve noticed that after a certain time the router drops off the network and I can’t ping it on 192.168.1.1, I’m forced to restart it then works then again after small period of time same things happens. I’ve currently switched back to 2860vac which works with same cables but dont understand why 2827ac is doing this making it unusable.

Probably nothing to do with your problem but the last time I had similar behaviour on my network it was due to an IP conflict