Might be worth a factory reset to see if it fixes it:
Make sure you can read all the default passwords on the base of the Hub before you do this
Unplug all ethernet cables
With the power on and the co-ax connected; press and hold the reset switch with a paperclip or sim removal tool for at least 60 seconds.
Allow 10 minutes to reboot, reset and stabilise
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Hub 3 - Modem Mode - TP-Link Archer C7