I've noticed several threads on this forum that discuss inbound connection problems when using MyHouse.
If it's true that MyHome can use only port 80 (I haven't tried it myself), then I suspect the mostly like cause is that these folks' broadband ISP's are blocking all inbound traffic on that port.
The reason is that the user agreements of most residential-use broadband providers prohibit the implementation of public web servers on home networks. Actively blocking outside access on port 80 is the primary means of enforcing this restriction.
It's generally easy to move a home web server to another port, but at that point, it basically becomes a private server since users must know the port number in advance in order to connect.
I was considering the purchase of a MyHouse, but if port 80 is, in fact, the only port it can use, then it's a major problem for me (my ISP, Cox Communications, blocks inbound port 80 traffic) and probably for most other non-commercial broadband users as well.
X10 must implement an option to user other ports. I've used a lot of server software applications of various types on my home network over the years, and they ALL allow changing access port numbers.
By the way, one workaround to the problem is to try using remote control software, such as the many free versions of VNC, to gain remote access to Active Home Pro.