If you’re experiencing the “unable to connect to authentication service” error when playing League of Legends, you could have any number of problems.
It could stem from a faulty internet connection, a disrupted firewall, or something else entirely.
The error message may occur during champion select, at the login screen, or mid-game. Either way, the issue is relatively simple to fix. The first thing you should do is check your server status. There’s a chance the issue isn’t at your end the server is down. If this is the case, all you can do is wait. To check your server’s status, click here.
Once you’ve checked your server and everything is in order, log back into the League client and load up a game. If the error message pops up again, try to troubleshoot and update your firewall. Sometimes, for whatever reason, firewalls block access to your internet connection, causing this issue.
In regular circumstances, firewalls aren’t meant to block your communication with League, however, if they’re out of the date, they tend to malfunction. To fix this, you can either disable your firewall altogether or update it.
If you’re using the default Window’s firewall, you can disable it by clicking Start, Control Panel, then System Security. Once you’re there, navigate to Windows Firewall, and click on Turn Off.
If that doesn’t work, there’s one last solution you can try. Temporarily changing your DNS settings is a quick fix to the problem. To do this, open Control Panel, click on Network and Internet, Network and Sharing Center, and then Change adapter settings. Once you’re there, right-click on your network (either Ethernet or Wi-Fi), and select Properties.
Next, choose and check the Internet Protocol Version 4 (TCP/IPv4) option, and once again, click Properties. Now, click the Use the following DNS server addresses option and change it to Google’s Public DNS. To do this, type 126.96.36.199 in the first box, and 188.8.131.52 in the second. After that, you should be set. Finally, load up League and all your problems should be solved.