Are these issues always due to an issue with BT Openreach connection?
This is not always the case. The connection for telephone/broadband is provided by BT Openreach however customers choose their own broadband/telephone service provider (BT, Sky, Plusnet etc.) Connection issues can sometimes be due to the service provider and not BT Openreach. In the first instance customers should always approach their telephone/broadband provider and then BT Openreach.