say you have a world called TEST123:

run the server on the same PC? yes(1) no(2)

1:
- got to your server folder
- open the file start_headless_server.bat with a texteditor
- edit last line to "valheim_server -nographics -batchmode -name WHAT_EVER_YOU_WANT -port 2456 -world TEST123 -password secretword"
- run the start_headless_server.bat
DONE (i see my server nowhere, can only connet to them over "direkt IP", works fine)

2:
- go to the folder User/YourUSER/AppData/LocalLow/IronGate/Valheim/Worlds, there you see 4 files TEST123.fwl TEST123.db TEST123.fwl.old TEST123.db.old

- copy thes 4files with the same folderstrucure to you server
- got to your server folder
- open the file start_headless_server.bat with a texteditor
- edit last line to "valheim_server -nographics -batchmode -name WHAT_EVER_YOU_WANT -port 2456 -world TEST123 -password secretword"
- run the start_headless_server.bat

should work with "direkt ip connect"