wi fi extenders typically double the range, half the speed don't they? if the issues is old thick walls, power lines sound like the best bet, I just got a tp link powerline
https://www.amazon.co.uk/gp/product/B01FFBN4MO/
when tested, I had almost no losses either (to my surprise) and I have 70's dodgy wiring
You can get a slightly slower model with Wi Fi too (TP Link)