v2 has been EOL for 3 years. Create a Sonarr backup.
Update to v3 - https://services.sonarr.tv/v1/download/main/latest?version=3&os=windows&arch=x64&installer=true
Ensure there are no further issues, and create another backup.
Update to v4 - https://services.sonarr.tv/v1/download/main/latest?version=4&os=windows&arch=x64&installer=true
See if the issue continues. If so, follow the steps here - "Unable to connect to remote server" since new server last month (hello from Reddit).