I can't play JP On Nox

too lazy to type it out but you should be able to find the fix as NA recently had this start happening at the beginning of the prisma codes event. If you go to the fgo subreddit and just search "nox" and sort by recent, you should be able to find the solution pretty quickly

Nox is hit or miss, I've had it not work for a while just to log in and work perfectly. Reddit sometimes has a fix.