This morning when accessing YouTube from TV, there’s no response. Found that the reason was internet access failure though WiFi connection was fine.
Then some other things got wrong due to router issue.
All the web hosting sites in local virtual server were down. The problem was port forwarding records all disappeared. I guess that after rebooting the router some configuration was corrupted.
Even worse, once adding back those port forwarding records, there’s error message about something like IP conflicts.
Restore previous configuration backup
Sometimes a buggy device is bad. This time there are double bugs. First, configuration settings (port forwarding) unexpectedly corrupted; then the previous port forwarding became zombie configuration records. New addition of settings create conflicts.
Netgear Nighthawk MR60: firmware ver. 18.104.22.168