my money is on the wifi connection being flakey. can you connect the tv by a Cat5e/6a ethernet cable. Even if just as a temporary one evening test (trail it around the house) to see whether the problem goes away. That should pinpoint wher to look next to fix the problem permanently.
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John
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My services: HD TV on VIP (+ Sky Sports & Movies & BT sport), x3 V6 boxes (1 wired 2 WiFi,) SH2 in modem mode with Airport Extreme Router. On VIVID200, Talk Anytime Phone, x2 Mobile SIM only iPhones.