How to re-enable DNS? Or how to enable them in general?

For me this is the weirdest problem ever.
I've configured a laptop with Sophos UTM9 installed, with home licence.
It runs as a VPN endpoint, to allow me to host a small website - it basically connects to a unit with public static IP, and does all the WAF functionality.
My UTM is connected to a mobile broadband router. The server that hosts a website is also connected to a router. There are also 2 desktops in the lan.
The IPs are as follows:
-router: 192.168.0.1/16
-UTM Internal: 192.168.0.254/24 (192.168.0.1 set as a default gw)
-UTM Internal-second address: 192.168.66.254/24
-server's IP: 192.168.66.2/16
-desktop #1: 192.168.0.66/24
-desktop #2: /taken from DHCP from a router/

At now every machyne pings everyone in this lan - UTM pings both router and a server, UTM pings remote unit's IP, server pings both router and UTM, server accesses the internet through the router, even the website is accessible from the internet (through ASG unit, VPN, and my UTM).

There are 3 hosts set in Network Services -> DNS section, reachable from other hosts in the LAN.

In the Firewall section there is a rule saying: from Any, protocol Any, to Any, allow.

The problem is: UTM is not able to resolve DNS names, nor ping the hosts in the internet.

Where could be the error?