Quad9 DoH keeps generating DNS log warnings, but it works

[2bn2t]

Did you use the Script from the other Thread?
What else did you do?

Problems with DoH, set standard DNS as fallback?

You can use this trick to make RouterOS use multiple DoH servers from different providers simultaneously: If one of the DoH services fails, you'll still see some error messages in the log, and a few queries might fail, but afterwards they will succeed when RouterOS switches to the other servers. But of course, this config will distribute your DNS queries over the listed DoH services, and you cannot prioritise just one and use the rest as failover