Domain names not properly resolved in Ubuntu 24.4 albeit the tunnel is "up and running"

[Onturenio]

Hi, I'm having problems to use openfortivpn 1.21.0 on Ubuntu 24.4 LTS. It used to work nicely on 22.4 LTS. The connection seems to work just fine. I can get access to the webs in my intranet if I use the exact IP number, but I cannot use names having instead the error DNS_PROBE_FINISHED_NXDOMAIN. I have been reading various issues here before posing this question, but I still cannot find the solution.

I'm using the following command:

sudo openfortivpn $IP:$PORT -u $USER --trusted-cert $CERT --$PASSWORD

With this, I get the following log:

INFO:   Connected to gateway.
Two-factor authentication token: 
INFO:   Authenticated.
INFO:   Remote gateway has allocated a VPN.
Using interface ppp0
Connect: ppp0 <--> /dev/pts/6
INFO:   Got addresses: [172.24.37.11], ns [172.24.96.17, 8.8.8.8]
INFO:   Negotiation complete.
INFO:   Negotiation complete.
local  IP address 172.24.37.11
remote IP address 169.254.2.1
INFO:   Interface ppp0 is UP.
INFO:   Setting new routes...
INFO:   Tunnel is up and running.

And as I said above, this kind of works, but I must us IPs instead of domain names.

Now, after reading some other issues, I have tried disabling resolvconf with this:

sudo openfortivpn $IP:$PORT -u $USER --trusted-cert $CERT --$PASSWORD --set-dns=0 --pppd-use-peerdns=1
INFO:   Connected to gateway.
Two-factor authentication token: 
INFO:   Authenticated.
INFO:   Remote gateway has allocated a VPN.
Using interface ppp0
Connect: ppp0 <--> /dev/pts/6
INFO:   Got addresses: [172.24.37.11], ns [172.24.96.17, 8.8.8.8]
INFO:   Negotiation complete.
INFO:   Got addresses: [172.24.37.11], ns [172.24.96.17, 8.8.8.8]
INFO:   Negotiation complete.
INFO:   Negotiation complete.
local  IP address 172.24.37.11
remote IP address 169.254.2.1
primary   DNS address 172.24.96.17
secondary DNS address 8.8.8.8
INFO:   Interface ppp0 is UP.
INFO:   Setting new routes...
INFO:   Tunnel is up and running.

This apparently adds DNS if you look at the log. But unfortunately the problem is exactly the same.

I have looked at the /etc/resolv.conf file but the content before and after running openfortivpn is the same:

nameserver 127.0.0.53
options edns0 trust-ad
search home

Any idea how to understand whats going on?

Thank you!