This happens to me, too. I can browse everything on the ROBLOX website, regardless of the type of internet browser, but I just can't play games. The message says the server is ready for me, but I never join, no matter how long I wait.
I can play ROBLOX games again, for some reason.
I tried reinstalling and it worked. I still have no idea why.
The only downside is that I can't edit my game in ROBLOX Studio. I can only play games.