GPON from MGTS started blocking ports?

Question

Computer networks

The Moscow apartment is connected via GPON from MGTS, ports 3389 and 5900 are open in the router (ZTE ZXA10 F660) for remote access, DynDNS is installed. Everything worked until recently, but now it has stopped. All obvious problems (DynDNS is lame, the internal IP has floated, the VNC server has fallen, etc.) have been checked and are missing. Technical support, either out of greed or incompetence, offers to buy a static IP, which is not needed, because there is DynDNS.
Who knows if they began to cut ports or is it still a technical problem?
Update: Looks like the answer has been found - https://www.youtube.com/watch?v=ndeDbUWZ2ys

Answer 1

Run nmap, check the router settings, then it will be seen