You already got the answer, so I’m bacically just wasting bandwidth and fightinn against nagger of Discouser, but…
This isn’t matter of the best hardware. It is matter of really old and outdated software and if some hardware can’t use any newer browser (out there is some lightweight options too) it is badly outdated too — and it is not something like iPhone8 vs. IPhone13 but trying to use 10 years old Nokia.
Discourse is not the only platform that not supports browsers that old. Actually really many services don’t work any more with IE5.1/XP.
I don’t know how things are word wide but in northern Europe all user agents, same as you are declaring, are 100 % only bots.