I was having a bunch of issues and went through several threads trying to find solutions. Thought this little guide might help some of you that are having issues.
Step 1: Create firewall rules on Windows(Windows defender)
1. Go to Windows defender
2. Go to Advanced Settings on the left side
3. option on the left side
4. On the right side click new rule
5. Choose option port
6. Next, choose TCP and in the specific ports field type 2456-2458
7. Next, Allow the connection option
8. Next, leave the 3 boxes checked
9. Next, Name the rule Valheim
10. Create a 2nd rule but instead of choosing TCP choose UDP and go through the steps
11. Next, option on the left side
12. Do the same thing we did for the inbound rules but make sure to click 'Allow the connection' by default it is set to 'Block the connection'. Add both the TCP and UDP rule.
Step 2: Forward the ports on the router.
Depending on your ISP and the type of router you have your GUI will look different compared to mine but you can find the same options looking around.
1. Click the windows start button and type CMD
2. In the black window type ipconfig
3. Scroll up and you should see something called IPv4 Address(note this address down)
4. Go to your router and forward both the UDP and TCP ports 2456-2458
5. It should look something
THIS NEXT STEP IS VERY IMPORTANT. LOTS OF GUIDES MISSED THIS.
6. If you see a firewall option on your router click on it and go to port forwarding. You will add a rule to port forward, but for the forward address put your PC IP that you noted down in Step 3. . Create a rule to forward both the the TCP and UDP ports to that IP!
Source: https://www.reddit.com/r/valheim/comments/s46w55/here_are_some_steps_i_went_through_to_make_my/
