My home setup is such that I use PiHole for DNS (dual PiHoles). This includes doing DNS for my local network as well as black-hole for a bunch of Ad-serving domains. To get this to work with Firefox, I've gone through all the settings to turn off DNS over HTTPS (DoH). The documentation on this is in a multitude of places, and seems to have a lot of "this setting doesn't exist anymore" pointers, but I get it working... sort of. Every few months (maybe every time Firefox updates?) Firefox stops seeing my local network names and starts showing ALL THE ADS. I go back through and LOOK AT THE SETTINGS (which ARE still set), but after LOOKING at the settings, it starts working as expected again for another however long. This has come to the point where I've stopped bothering to open Firefox when I need to get to my own network resources. DoH is already hard enough to turn off, but having to look it up every few months to "check" the settings so it's REALLY off is very difficult. This has been going on for at least 8 months, and I'm only bothering to mention it now because I've noticed that I'm changing my habits, Goocrosoftle is winning. So, MAYBE I'm still missing something. Half the articles point to settings that don't exist anymore, so maybe there's one more thing that will make this actually stick. Everything leading to the search HERE on this topic talks as if Firefox is still using the local machine's DNS, and that has not been the default for quite some time. Either way just adding my "inside." domain to the localdomains setting will not fix this problem.