Duntun? Never heard of this brand. Is it safe to use?

Is there any concern with whitelisting a cellular CGNAT’s public IP?

It depends on how much you decide to whitelist. In my case I whitelist my cellular carrier’s IP block. Which does expose those services a little more broadly but I’m willing to risk it.

Blacklist everything then whitelist the IPs you know you’ll be connecting from (work, cell phone, etc). I don’t connect from random places usually. If I need to then I use cellular. You might be better off with a VPN if you need to connect from random places.

IP whitelisting