@apt 

The MR600 is supposed to support IPv6, so if you enabled IPv6 then you should be able to avoid CGNAT because CGNAT is only used by EE for IPv4. You could connect from external devices to your router's IPv6 address (assuming you had IPv6 access at the external device).

I have tried to get dual stack IPv4 & IPv6 working with the MR600, but unfortunately when I create a new APN and select "IPv4 & IPv6", the router only seems to show an IPv6 address and the IPv4 address is blank. Does anyone have IPv4 & IPv6 working with EE?

@apt 

If you go to Advanced > Network > Internet and then select "Create Profile". Copy all the same details from the default EE profile, but change "Profile Name" to "EE2" and "PDP Type" to "IPv4 & IPv6". Then save this profile and make it active by selecting EE2 from the dropdown box under Basic > Internet > Profile Name and clicking Save.

To check if it is working, go to the Advanced tab and you should be allocated an IPv4 address and if you click on IPv6 it should show an IPv6 address. In my case, it only shows an IPv6 address and not an IPv4 address, meaning IPv4 does not work. I suspect there is some incompatibility between EE and the MR600. Please try this out and let me know how it goes. If you have the same problem, then we can raise it with TP-Link tech support.

@Cytec thanks for that, I've a set it up as you described and I'm also only getting an ipv6 address. Strangely using test ipv6 dot com shows me both ipv4 and ipv6 addresses.

Also I've also noticed that the speed test in the app no longer works.

I also contacted support. They replied to say "it is recommended to use IPv4 only". This is not particularly helpful so I will be returning the device.