I thought I had read the guide correctly and I have gone into the management area of the router and setup the external IP address I want to manage my customer's router from. Unfortunately when I go to the external IP address of my customer I don't get anything, I just get a page not displayed.

Has anyone else setup a Draytek 2860 for remote management directly from an external IP address?

make sure the ip address of the customer has not changed

i think he may need log in first (especially if he did hard reset because by default the settings are off) with the default passwords or the one he currently has and he need to go at System Maintenance >> Management > Internet Access Control > Allow management from the Internet & tik the http/https etc
there are some options as well at System Maintenance >> Administrator Password Setup that may need change if you still don't get access at management menu

once the ip is correct & the allow management is enable it should give you access but again you need to have the username & pass

We have an active teamviewer connection to the main server so we can see and change all of those settings. Will take a look now

Thank you

Got it working now, thanks. I had forgotten to enable the internet ports as well.