Make sure the program opens before setting up a connection. Installation errors and network errors happen at different stages: if the program won’t start, check the architecture, dependencies, and install permissions first. If it starts but can’t connect, check the subscription, server settings, and client logs. Downloading the installer again usually won’t fix an expired subscription URL.
Before importing a subscription, make sure the URL is complete and comes from a source you’re authorized to use. Don’t include spaces or line breaks when copying it, and don’t mistake a management page URL for a subscription URL. After the subscription updates successfully, select a server and test the connection. Seeing servers in the list confirms the import worked, but doesn’t guarantee the remote service is available.
Once the standard proxy connection works, configure routing rules, DNS, and TUN. Change one category at a time and note the original settings. That way, if something goes wrong, you can return to the last working state instead of guessing which of several changes caused it. If you use many custom rules, keep a simplified configuration as a baseline.