Cannot connect NextDNS on elementary OS 5.1.7 (Ubuntu-based)

Hello everyone!

I've been using NextDNS for a few days now, mainly on my Android phone and wow, scary, but thanks for giving us these tools.

The problem is on my pc. My OS is elementary 5.1.7 (Ubuntu-based) and I can't get it to work with either of the two methods on the wiki (curl and manual installation through apt).

The first time, with curl, it just crashed and I couldn't connect to the internet. Then, with apt, I connected to the Internet but no through NextDNS (obviously I did activate and run NextDNS).

Today I tried again, with the same result for apt, but with curl it worked partially: it uses DoH and detects NextDNS but it does not do it through my profile.

I followed this instructions from NextDNS knowledge base: https://help.nextdns.io/t/60htdyv?r=60htapc, but doesn't work (now setup-router=false). I guess is that the problem is on port 53, but what can I do to change the port?

I have not found any tutorial to install NextDNS-cli, but I have followed all the steps in the wiki. I don't know if anyone who has installed it on Ubuntu would be so kind to tellme the steps you have taken to compare.

Thanks in advance!

---- Images of my configuration and tests ----

https://i.imgur.com/25jOYGr.png / config

https://i.imgur.com/9Uu470x.png / test

https://i.imgur.com/oyakbQC.png / log