Assuming the connectivity is fine in your location - ask your neighbours whether they have any VM connection issues - then modem mode with the gaming router should be absolutely fine. Its the Hub3/4's poor wifi that's the real issue - but not a factor when in modem mode
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John
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I do not work for VM. 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 +2 Airport Express's. On VIVID200, Talk Anytime Phone, x2 Mobile SIM only iPhones.