Double domain names/url

I have a really strange issue and not 100% its cf tunnel related, but wanted to post here to see if anyone else has seen
my unifi controller is over a tunnel, if I enter unificontroller.co.uk to the address bar, I get auto populated unificontroller.co.uk/unificontroller.otherdomainiown.co.uk thus not allowing the browser to connect, tried, cookies, DNS, various browsers and different machines, even a different main router/dhcp/dns server but will happening,
any ideas peeps?
Stubbsy