[2021] Co op hosted world has constant 630ms

First time I hear about that, it looks like the connection to your friend is taking a very weird route. This definitely is a networking issue on your friends side. Can you check if, when you open the law page you get to the correct law page, to none at all (timeout) or to a law page of a different server? If the latter is the case, you are connecting to your friend via our relay server, as you otherwise couldn't connect to him due to incorrect network settings.

You shouldn't need any third-party software, actually. But it is known that Hamachi does not work well with Eco, though that is not an issue as you aren't intended to use such software in the first place. But glad it works :)