To exit modem mode and go back to router mode just disconnect all ethernet cables from it and with it still switched on, press the reset pin in firmly and hold it whilst the clock ticks round a full 60 seconds then release the pin and do not restart the Hub - leave it a few minutes and you will be in normanl router mode
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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.