src="http://addr:port"

u are displaying in another server on pi?

sorry, where is that web server?

you said u can access mm externally?
but then used the internal ip address?

my pi is at 192.168.2.44:8090
and my external router is 47.220.yy.zz
so I would have to use
http://47.220.yy.zz:8090
and have port 8090 forwarded from router to pi.

If I can get it working within the PI, I will set the site to run from it

Im currently using the following code with no luck (i’ve removed the size parameteres atm)

<iframe src="192.168.1.200:8080" ></iframe>

on your router, you will need to do some port forwarding, to allow systems outside your network to access systems inside… you will need to make sure the port number on the outside matches the MM port number. (some routers have the ability to save that config, even if its not active, so make sure its active too)

now you will need to FIND your router from the internet… most residential accounts use dynamic address assignment (DHCP), and there is no guaranty that the address will come back the same if there was a power off, of other unrelated disconnection.
I use a name-> ip mapper called dyndns.org, but there are a few of these.
(some routers have this built in, and will update the configured account whenever it gets a new address, there are also apps provided that run on windows that do this)

so I can get to my home machines with http://???.dyndns.org:port

then u should be able to view your home/campervan MM from anywhere
(note that I’ve had trouble with a couple routers where accessing the system with the external name/port while ON the internal network doesn’t work… )
I can test this by turning off wifi and using the cell network, as the towers are outside my house.