Wifi dropping on Technicolor TC7210, Sure signal on cable?

Hi folks

Wondering if anyone has experienced issues with wifi dropping on the TC7210 cable modem, and/or using a sure signal on the cable network?

I'm staying in a place on the Kapiti coast that's a mobile black spot so there's a Sure Singal here too. Periodically a Note 5, Macbook Pro stop working on wifi, but switching to mobile data (running through the sure signal) works. When wifi stops working the devices can see the wireless network still but can't join it, and the only solution I've found is power cycling the cable modem.

The cable modem is definitely still connected to the network 'cause the Sure Signal is still working. I was in a Vodafone shop yesterday and overheard that they don't recommend Sure Signal on cable - has anyone come across that too? Seems to work fine for us.

I'm thinking that it might be best to suggest they switch to fibre, but wondering if anyone has any other solutions.

Cheers