Looking for logging into the Unity Service Not Available site and are not getting the correct working link for it? In such a case, you can use the links given here by searching your desired login page in the search box. If the page is present on our website then you will get all the links related to the Unity Service Not Available site. After that you can login as usual with your login credentials.
https://answers.unity.com/questions/1003966/error-service-not-available-please-try-again-later.html
https://forum.unity.com/threads/service-not-available-please-try-again-later.522435/
http://answers.unity.com/questions/1219341/service-not-availableplease-try-again-latermy-syst.html
https://feedback.unity3d.com/suggestions/service-not-available-please-try-again-later-and-problems-with-licence
https://docs.unity3d.com/Manual/SettingUpProjectServices.html
https://unity3d.com/de/unity/features/multiplayer
https://forum.unity-community.de/topic/14510-login-service-not-available/
https://askubuntu.com/questions/776991/cant-login-unity-game-engine-on-ubuntu-16-04-lts
https://stackoverflow.com/questions/46506184/unity-license-error-on-startup
https://community.playfab.com/questions/910/210604407-Error-on-Login-Service-Unavailable.html
http://community.avid.com/forums/p/184030/855773.aspx
https://gist.github.com/orejuelajd/79b12befb938f7163a50f8cc65a9b6d0
https://www.dellemc.com/en-us/documentation/unity-family/unity-p-software-upgrades/05-unity-upg-br-troubleshooting.htm