One last post I think! After a few days of testing, everything seemed to be working good for 2-3 days, then back to loosing signal after 10-15 seconds until a channel change, where it would be the same problem....
I ended up having to get a 5 port netgear GS105E (supports IMGP snooping / Multicast) to separate my STB's from My network. I expect It may have had to do with my Procurve 1810G not supporting management of multicast, From what i've read my previous issue with loosing signal on any given channel after about 10-15sec was related to the Multicast stream starting, since I've added the second switch and moved my IPTV to a single port on the AC-3100, everything seems to be running smooth again, the PVR & STB's have IP's outside of my network.
Thanks for sharing your experience. Just wondering in your final setup, are you able to watch all the "in-home only" channels on your Optik TV app when connected to your own router?
Somehow from my testing, putting the STB on its separate vLAN means losing access to the "in-home" shows on Optik TV app when connected to own router.