Am waiting for a call back from Spark currently but thought I'd post here to see if anyone has ever seen anything similar. 

Brand new Spark Fibre 100/20 connection at a friend's place - was connected on Wednesday. Been playing up since it was connected. Works perfectly when it goes but randomly it seems to disconnect and they cannot browse the net (on multiple devices, wireless and hard wired).

It's almost like the router (Spark HG659) is dropping the PPPoE connection but I've not been in front of it to have a look when the issue occurs. Apparently the internet light doesn't go off when the issue occurs. 

The optical light on the ONT is always green/flashing and the landline phone works fine. I've put in another brand new Spark HG659 and the issues are apparently the same. When Spark call back later on I'll pop around and see if they can see anything odd - I know I've not provided a lot of info, but has anyone seen anything like this before?

I'm sure the HG659 should be able to handle the network. We're talking 2x wired devices (one AP in an outside room, one PC) and around 7 wireless devices most of the time- 3x phones, 1x laptop, sky decoder, TV. The network has been rock solid with all the same gear bar the HG659 on ADSL up until  the Fibre was connected.