@alecor, I tried everything I could think of including all the suggestions here and I was never able to resolve the issue. Unfortunately I had to return the router a few weeks later. I ended up with...

Thank you for the response. I enabled the DMZ for one of the camera's and also tried changing the port via DVR and virtual server, yet same issue. Either doesn't work at all, or works for a minute or...

Recently switched from an older Netgear to the AC5400X. Enabled port forwarding via virtual server for my Security Camera's. All settings seem to be correct and it will work for about 30 seconds or...