I'm having the issue with NordVPN – I've tried using it from Windows 10, Android and iOS and got the same problem on all 3, however as soon as I switch to a 4G connection or to a different WiFi network it works fine.
Looking into this further, it actually seems to be a wider issue with connecting to anything that doesn't use the most common standard ports. e.g. applications using port 80, 443, 21, 22, 465, 995 all work fine, but applications that use non-standard ports do not. e.g. I cannot fully connect to a passive FTP server as that uses ports between 30000-50000, I cannot access any cPanel/WHM web hosting dashboard pages as that uses HTTPS over ports 2083 and 2087, I cannot use Speedtest.net as that uses port 8080. I can connect to SSH on port 22 but not if it uses a non-standard port e.g. 2222. Discord audio won't connect as is uses ports between 45000-60000.
This was all working last week and I've not tinkered with the router settings in recent weeks. I did take a look at my router's Firewall setting just now though which has always been set on High. I tried changing it to Medium and then all my problems went away. It has definitely always been set to High though and never been a problem - maybe it is an error with the implementation of the High setting in the current firmware - or is it actually that High never worked correctly before and now does?
If there is a newer firmware available that we can try, any time you can commence installing it would be fine, I understand it may take 15 minutes.
