Never had a Hub4 (or a Hub3 for that matter) so this may be cobblers but...
If you log into the Hub4 settings can you see a Configuration Settings Page (or similar) in there - if so look for boxes called Maximum Data Transfer Rate for up and down channels and see what numbers are in there (may be in bps not Mbps). Just wondering if your recent upgrade didn't go through properly to inform the Hub let the new speeds through
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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.