Plusnet Hub2 router not seeing ethernet connections

[#1]

Just switched from FTTC to Full Fibre (both with Plusnet) and new Hub2 router works fine on wifi.  Have tried to connect devices to ethernet ports with variable success.  Ring alarm hub works fine.  Linksys voip-phone adapter isn't seen by the router (and doesn't work).  Neither does my TP-Link range extender, when configured as an Access Point on the end of the cable - it's broadcasting fine but is showing no internet connection.  Have checked the ethernet cables and ports by connecting my laptop, and the router sees that no problem, and internet works fine through the cable, so have ruled out problems with the cables and ports.

Any suggestions as to what might be the problem?

TIA

[#2]

@MartynB welcome to the forum.

Which TP-Link range extender are you using? How have you configured its network settings, Manual or DHCP. If there is a DHCP server on the range extender I would suggest turning it off.

[#3]

@MartynB 

If you had a Hub 1 with FTTC then this will work with FTTP, just use the WAN rather than the dsl connection. The only limitation, apart from inferior wireless performance is that upstream speed is limited to around 30Mbps.

If you try this it should confirm that you have made no other changes, apart from any that you have made to the hub default settings on one or the other..