Registration of DHCP clients in the DNS server stopped working in 2.4.x

  • Hi,

    in my labs setup the pfSense firewalls are the DHCP servers
    there are 2 DNS servers in the labs : x.x.x.60 MS Server and  x.x.x.15 (pi-hole) and

    in the dhcp server settings, it is set that pfSense should register the clients in the .60
    until 2.4.0 that seemed to work well, since the upgrade to 2.4.3 (I don't know about versions in between) I no longer can save the dhcp server settings, if I don't enter  DNS Domain key  and  DNS Domain key secret .
    I don't need them, as the MS DNS cannot be secured (no AD)
    The DHCP.LOG is filled with messages like

    Unable to add forward map from android001.internaldomain.tld to x.x.x.79: tsig verify failure 

    but the MS DNS server will even not ask for the key & secret

    I cannot see more detailed info the logs if it even tries to connect the MS DNS server

    How can I fix this again.