Phone UI not accessible on certain subnets

[gavdcedfqwe]

When clicking the "phone UI" button from the 3CX management console, I'm unable to connect to phones on these subnets...
192.168.1.x
172.16.3.x

I am able to connect to phones on my local subnet and 172.16.8.x
The phones I am connecting to are at other sites, connected by transparent IPSEC tunnels.
I can ping.
The phones work perfectly.
I'm just unable to access the "phone UI". - ie http://admin[email protected]/
It just appears to be chrome that can't do this. IE seems to work.

I suspect some kind of clever routing built into Chrome but cannot fathom it out.

 

[Saqqara]

Can you access the phones, just by IP address in chrome - http://192.178.1.x

 

[gavdcedfqwe]

Yes, can access via http://192.168.1.56
it's just the links like this that don't work http://admin:*******@192.168.1.56/

They work when used in Chrome on the same subnet as the phone.