The Agar.io team was aware of a connection issue when entering the game through the web version.
After an investigation the issue has already been fixed.
The issue was related to the FFA mode of the game but all other modes were up and running.
Since some of you were having difficulties accessing the other modes, in the future please use the following links when coming across issues of this nature:
We thank you all for the reports and feedback you sent through our support desk and our social networks.
The team Agar.io wishes you all the best and good luck in your matches. 😉