I am new to the community. Please, forgive me if I am asking for the thing it was asked before.
A week ago I set up the Synology with zerotier. Everything was working perfectly good. But this week my dad (Lithuania) cannot connect to My NAS (United Kingdom). I tried to connect from my side it works, but I released because I am locally connected to my NAS. I did not set up or did any changes for NAS set up. It runs the latest zerotier. Any clue where I should start to look to resolve the problem?