Can't access certain sites even if they are ok on mobile for example

Support & Help Requests
1

I had this issue and I wanted to write somewhere the solution to it.

In Firefox
Preferences->Network settings and Enable DNS over HTTPS.

The hint was: https://www.linuxquestions.org/questions/linux-newbie-8/can't-access-https-sites-in-firefox-fresh-ubuntu-6-10-install-506164/

In Chromium I can't figure out how to enable DoH.

EDIT:
When running Chromium under a supported desktop environment, the system proxy settings will be used. However, either your system is not supported or there was a problem launching your system configuration.

But you can still configure via the command line. Please see man chromium-browser for more information on flags and environment variables.

EDIT 2


But even if I install dnss and run

dnss -enable_dns_to_https -https_upstream="https://1.1.1.1/dns-query

the url https://1.1.1.1/help
still displays :

|Connected to 1.1.1.1|No|
|Using DNS over HTTPS (DoH)|No|
|Using DNS over TLS (DoT)|No|
|Using DNS over WARP|No|

Final edit

I managed to do it with https://www.configserverfirewall.com/ubuntu-linux/ubuntu-set-dns-server/
I put 8.8.8.8,4.4.4.4 or 1.1.1.1 in additional DNS in IPv4 and flushed the cache with
sudo systemd-resolve --flush-caches.
After that I disconnected the network connection and connected it again.

More info on DoH

2

This was the solution for chromium and chrome. If it is done the firefox setting is not necessary any more: