6in4 and DNS problem

I am with Omnia 2020 with TurrisOS 6.2.1 (HBK). I am experiencing a strange problem when trying to activate 6in4 via the Hurrican Electric service, which I have profitably used in the past. When I set the HE parameters on TurrisOS, either via reForis or via LuCI, the connection to the tunnel is established, the reForis check gives me both IPv4 and IPv6 connections active, and DNS working. But at the same time all devices connected to the LAN stop resolving domain names. I have tried restarting both the router and the devices, but everything remains non-functional. If I try to ping the domain names in the Turris OS shell, the router resolves them correctly. What can it be? Like DNS requests are no longer going through the LAN. The only solution for me is rollback, because even if I take out the tunnel or the whole WAN6 interface, the problem remains. As if I had viloed a sacred law.