It seems that you are having some issues with your Slingbox PRO-HD since the video signal drops after a short period of time.
According to the provided information, this issue seems to be related to the connection speed. Keep in mind that the Slingbox PRO-HD has some requirements and they must be met specially if you are streaming a HD signal. I encourage you to contact your current ISP at the remote location and ask them about any possible bandwidth usage restriction, since the connection speed drops dramatically to 115mbps.
I also recommend you to check this article in order to verify that both of the locations (the local area network where the Slingbox is and your current remote location) meet the requirements for the Slingbox PRO-HD:
Hope this helps!