New router installed still dropping out

[#1]

Help I am not at all technical so floundering!! I have super fibre broadband via open reach cabinet. I recently had issues with internet dropping out and was recommended to install new router. I received and installed Plusnet hub one, connected to telephone line via open reach modem.  I gave this 2 weeks to settle. It is not as bad but frequently drops when using FaceTime/Skype and now Sky will not work properly, saying no internet connection but when I check on settings shows all connected.

Help any advice on the best way forward would be greatly appreciated 

[#2]

Remove the Openreach modem, it is not needed with the Hub1

[#3]

Thank you I have disconnected the modem. Contacted Plusnet today, there was an issue with the new router, reprogrammed and all now seems ok .