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 halfway through a game. Either way, the issue is relatively easy to fix.
The first thing you should do is check your server status. There’s a good chance the issue isn’t at your end. 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’s status and everything is in order, log back into League and load up a game. If the error message pops up again, your next course of action is to troubleshoot and update your firewall. Sometimes, for whatever reason, firewalls block access to your internet connection, resulting in this issue.
In regular circumstances, firewalls aren’t meant to block your communication with League, but if they’re out of date, they tend to malfunction.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. Temporarily changing your DNS settings is a quick fix to the problem.
To change your DNS settings, open the Control Panel, click on Network and Internet, Network and Sharing Center, and then Change Adapter settings. 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. Lastly, click the Use the Following DNS Server Addresses option and change it to Google’s Public DNS or any other alternative. To do this, type 184.108.40.206 in the first box, and 220.127.116.11 in the second.