I have one domain registered with Dynu that I use DDNS to point at my home router. It works fine. Requests coming in on port 80 and 443 get routed to a VM running NextCloud. Port 32400 points to another machine running Plex.

Now, I would like to add another domain that will point to a VM running a web server. I know that I'd have to set up DDNS for that domain to point to my home router, but what do I have to do on my router to direct port 80 requests on domainA to the NextCloud VM and port 80 requests on domainB to the web server?