@xhjt6ibnm3juxprtuown said in Cannot find a setting to control adding www to addresses:
When I go to https://subdomain.example.com, Opera adds www. to it, resulting in https://www.subdomain.example.com, which does not exist.
Does not do that here - it reports that "subdomain.example.com" does not exist (This site can’t be reached).
Is it possible that real server (not example.com) makes redirect to wrong address?