FaceTime shows poor connection after 8.2

The problem is that since the last software update to 8.2 my Facetime will not connect correctly. On all devices (iMac, iPhone 5s and iPad Air) when I try to FT I see the person for a few seconds then the video stops with a message ‘Poor Connection’. The other person can still see me and the audio remains.

My Mac is connected directly to my Viasat satellite modem and my iPad and iPhone connect to an Airport Extreme. Diagnostics on the modem show a strong signal and the Extreme has always given a strong signal. I have no problem streaming movies from iTunes of watching HD on my Slingbox. I can use Skype video call with no problems. Download is @20meg and upload @ 6meg.

For some reason FT seems to think that my connection is poor and will not give me a video link. Prior to recent updates all worked very well.

I have re-set the modem, restored the Extreme to factory settings and re-installed, stopped and restarted FT on all devices, re-set internet on iPad and iPhone. Turned everything off and restarted but no joy.

I have been able to make calls on a friends network but it seems that FT does not like my network anymore. The fact that my iMac FT will not work when connected directly to my modem seems to imply that recent software updates no longer work successfully with my Viasat modem.