Connection Issues

If you are having problems connecting to rooms try the following things

Run WebRTC Diagnostics:

https://www.haxball.com/webrtcdiagnostics

This page will run a set of diagnostic tests regarding WebRTC, the expected results are:

• Srflx candidates found: YES
• Host candidates found: YES
• Symmetric NAT found: NO

Users that have Symmetric NAT will be unable to join rooms hosted by other users that also have Symmetric NAT. This is a router problem.

If no Srflx candidates and no Host candidates are found it's likely that your browser is blocking WebRTC.

Disabling adblockers and all extensions

Some ad blockers or extensions will prevent webrtc from connecting, see if disabling the ad blocker fixes the problem.

Try with a different browser

If you normally use Chrome, try installing Firefox and trying with that. If you use Firefox then try installing Chrome.

Disable Chrome Flag 'Anonymize local IPs exposed by WebRTC'

If your computer has a public internet ip then this privacy feature can cause problems connecting to others.

Go to the url chrome://flags/ and disable the feature called 'Anonymize local IPs exposed by WebRTC'.

Whitelist on Firefox obfuscate host addresses

If you're on Firefox 74 or later, go to about:config and find media.peerconnection.ice.obfuscate_host_addresses.whitelist.

Edit or double-click to add www.haxball.com domain.

Try to find a NAT setting in your router

Some routers allow you to configure the NAT behaviour, the name of this setting can vary between routers. Look for the words:

• full-cone
• restricted-cone
• port-restricted-cone
• NAPT
• symmetric-nat

They are ordered from best mode to worst mode.

Most routers don't have this option so don't get your hopes up.

Enable DMZ in your router

Enabling DMZ and pointing it towards your computer can improve the symmetric nat situation. For this you will need to set up your computer to use a static ip address instead of dynamically obtaining one with DHCP.

Keep in mind that DMZ makes your computer more accessible to the internet which is generally bad for security.

Forward all UDP in the ephemeral port range

If you are using windows vista or higher the ephemeral port range is 49152 to 65535.

Forwarding UDP in this range to your computer might improve the situation. For this you will need to set up your computer to use a static ip address instead of dynamically obtaining one with DHCP.

Reduce the number of routers to a minimum

If your home network has more than router between the internet cable and your computer then try connecting your computer to the first router. The less routing the better.

Set your router to bridge mode

If you are fine with having a single computer connected to the router, then setting it as bridge will get rid of NAT and probably improve the situation.

Replace the router

If all else fails then you can try replacing the router for a different model. Sadly the NAT mode is usually not advertised so there's no good way to know if the router works properly without trying it.