Sometimes just a good ol’ fashioned reboot of your entire internet connection(router/modem) does wonders. I do it about once a week. When I see a ping over 5 and DL speeds(in msfs) in the 20’s I go up and unplug and plug. Ding, back up to 100+. Funny in ‘native’ xbox, I never have slow downs getting patches for other games, sometimes hitting 850+mibs for say the newest COD 4 gig patch-but MSFS marketplace will be sub 20 in the exact same session. Often though it will only be between 100-200 from MP, but at least tolerable. It’s hard to tell because it breaks to decompress/install and start up, so the counter can’t get up to registering full speeds. It also seems to help live traffic and other things.
Back when I thought re-installing the game ‘fixed’ anything(which it never does) out in the native xbox menu as an install it would hit 400+ like a game patch.