I have a rather odd problem. I have a bunch of TP-Link NC200 cameras which were connected to my ASUS RT AC88U Nighthawk router and working fine. A few months ago the router abruptly went offline and I had to restore the settings from a previously saved configuration file. Everything was restored successfully EXCEPT the camera NONE of which connect to the router now. "Everything" here includes a wired FreeNAS server, an NVidea shield box, a bunch of what bulbs, SmartTV, etc. 

Measures taken include

1. Reset each camera by long pressing the WPS button then trying to connect using BOTH the WPS method and the method
2. Rebooted then reset ASUS nighthawk router multiple times
3. Bought a new NC260 camera thinking ALL the cameras were dead - SAME PROBLEM
4. Connected the cameras to an older ASUS RT N66U router that's connected to a different ISP (we have both a fiber and cable modem). This time it DID connect!! However, the viewing speed is a lot slower as the cable internet has low bandwidth. 

I really don’t understand the problem here. I suspect it's got something to do with router settings but I am not savvy enough to pick up what the problem is. Not sure why the cameras connect to one ASUS router and not the other. 

Thanks in advance