If the message "Failed to connect to map server" remains even though other maps are working, but a particular one just will not work for anyone, it's most likely due to the game server is having issues with the particular map and the process itself is stuck.
The only known way to fix this is if we have a full server restart. We have them once in a while so the map(s) will most likely start working after that.
I believe your initial issue was this with the particular map "crossways". I think it's more likely that a map get stuck like this on the "failed to connect to map server" if people go in and out of it a lot since it means the map process will shut down and start constantly, while a map like Bonfire or Fluorite in the game always have some users in it which keeps it running all the time.