Get online support
I forgot to tell that it's no issue having internet before. It suddenly happened 2-3 months ago.
Ok @gungurru I've just setup an iPad mini 1 running iOS 9.3.5 and connected to a HG659 running firmware V100R001C216B112 it connects no problem to either 2.4 or 5ghz bands, at this point i would do a factory reset on the HG659, you won't need to enter any login or VOIP details as it will auto configure to the network again, just allow a few minutes and see how you go.
All fixed and solved my problem for the last 3 months. Thanks again