RMS VNC Not working

Sorry for the insistence, but I’d like to understand why VNC links often have problems. The credits inside the router are always there, and updates are always done to the latest stable version.
It worked for about an hour earlier and now it doesn’t. Also, it only worked on the PC and not on mobile devices.

I’m waiting for explanations to give to the customers.

Thanks in advance

Thanks in advance.

Best regards