No connection to server outside local network

Hi,

I have RustDesk server installed on my Synology in a docker. Version 1.1.9 worked fine, but since 1.2.1 update I get no connection when I try to connect outside of my local network.

DynDNS, ports, etc. has not been changed since 1.1.9 and I already reseted both, router and nas. I also completely deleted docker and reinstalled - unfortunately all without success.

Any ideas what could cause blocking access from outside? As said connection within my local network is no problem.

S.