We have “D Link cameras but on a recent trip away our cameras lost connection with the router and could not reconnect!
This happened once before and it took a reboot of this new expensive router to reconnect.
So I phoned a friend and he went to our country yard and switched off the main breaker for a minute, which rebooted the router and I was able to reconnect to cameras before he got off the yard. I snapped a picture of him.
I googled this issue and it is common.
Mysolutuion is this. I put a timer on the router and once a day every day it turns off for a short period of time.