The issue is with the Token for the Connection. You cannot go anywhere and extend it, you have to use the account / connection to keep it alive as over time this will expire as refresh tokens are not forever.
That being said, you can verify for me what type of account you are using (Service (Just a licensed account), Actual Service (App registration), a person) etc for the connection, which is possibly just you if you created everything.
Things that I do depending on if its a custom connector or built it
I create a simple power automate flow and I schedule it to run (if its super important) every hour) and have it use the connection you want to keep alive. You also need to validate whether the account you are using is bound by the same rules as everyone else (has MFA, must change password every X Days) etc etc as all of this impacts how often your connection gets impacted, although not specifically (but sometimes) for this issue.
Its simply put, if too much time goes between when a connection is used and when its not, or if the password changes etc, it will stop the connection from working.
If you are using a custom connector that is using its own built in Auth, then you need to have that get refreshed (somehow because any token from any platform) is not good forever.
If these suggestions help resolve your issue, Please consider Marking the answer as such and also maybe a like.
Thank you!
Sincerely, Michael Gernaey