If you cannot connect to the Bisq network repeatedly and if you have not already setup Bisq (account, funds,…) you can simply delete the data directory and start over again. Be sure to not have BTC, offers, trades, disputes open… when you delete the data directory all data is gone.
If you have already setup Bisq the above option is not recommended. See below another option (restart router) which you could try.
We are investigating what causes the issue but it is likely related to Tor as there have not been changes in Bisq in that area since long and there have not been many such issues but recently they seem to happen more often.
It might be that a onion address or your IP address get flagged by the Tor DDoS protection system (false positive) or other unknown reasons. I have observed when I had a development app which got repeatedly connection problems and I renewed the data directory to get a new onion address that is often solved the issue.
If your IP address got flagged and if you have a normal consumer internet connection a restart of the router will usually give you a new IP address.
Here is a user who run into that issues and I saw it locally for me as well a few times the last days: