After flashing it with that firmware, it becomes unreachable. I see an open dd-wrt wireless network ant it responds to ping's, but other than that ist useless. I cant get any reply from it from my browser on 192.168.1.1 after it reboots.
I can reboot it back to the Linksys stock firmware on the other partition by power cycling it 3 times.
Thank you spuriousoffspring, that made me think a bit in that area of troubleshooting.
I did try and close and then open my browser, but that dident do anything. Im normaly using Firefox as browser. As it turns out, the web gui that the router starts up with after being flashed, arent supported by Firefox...
I opened Microsoft Edge, and the router were once again visible and and I can now further work with it to try and setup OpenVPN on it.