Hello, there's a lot of resource here and on our discord with the dedicated server setup. Please check here: https://valheim-server-help.github.io/ and make sure all the firewall ports are properly open for the machine hosting your server.

Discord link: https://discord.gg/valheim

Also maybe ask in the Discord if someone from outside of your network can try and log in. Try also connecting to your server by its hostname from the same subnet as your server (the name of your computer hosting Valheim). Good luck!