Open firefox and type:


Search for:


Probably you already have:

If not add it or use something like:

Then enable network.trr.mode by setting it to 2

Set network.trr.mode to 2 make DNS Over HTTPS the browser's first choice but use regular DNS as a fallback (0 is "off by default", 1 lets Firefox pick whichever is faster, 3 for TRR only mode, 5 to explicitly turn it off).