First, check that it isn't Windows Firewall. You'll have to allow it in "allow an app through windows firewall", your antivirus, and make an inbound rule both for the program on TCP port 42420 and a generic rule for allowing TCP port 42420 in Windows Defender Firewall with Advanced Security.
I've had trouble with Windows Firewall unless I did all three or even four of those.
And even then, Vintage Story might not even be listening on the right network interface, for either Hamachi or your LAN. IPv6 can cause issues too.
Otherwise, you could use standard portforwarding, but if you have Comcast and you are using the stock cable modem with Comcast you will NOT be able to portforward, regardless of if you add the port or not. The problem is that portforwarding, either intentionally or unintentionally, was broken in the firmware years ago. It says it does it, but it does not. Here's the safest way to do it otherwise:
Put a Linux server on your LAN, and look up the obligatory steps (installing, generating an SSH key, copying it to the server, disabling password authentication, fail2ban, ufw, etc)
Either follow the dedicated server instructions or use rinetd to forward the port from your PC's IP
DMZ the entire server, exposing all ports on the server directly to the internet
I would recommend not putting your Windows PC under DMZ. Windows has a lot of network services that it runs that could lead to your PC being compromised remotely.