Hello The Fish,
to my knowledge our current UCS 4.0.x Release does not support any offsite installations. Only a local LYNC with a local exchange is supported.
As its all Exchange UM, what constitutes an "offsite installation", is there a limited number of hops, or a restriction of having to be on the same network segment or something else?
For others reading this thread: It seems like its NAT thats the issue, with 4.0.x not able to do STUN/ICE, and 4.1 offering this (release coming soon)
That is correct, the current release does not support Edge media traversal.