JGS524 conflicting with Apple AirPort Extreme when creating network

I have a home network set up as follows:-

Virgin Hub - 200mbs connected directly to an

Connected by ethernet and set at DHCP & NAT to an Apple Airport Extreme

I have created a Network with this and then have an ethernet cable going into the NEtgear Switch JGS524.  I have 4 airport Expresses peppered round the house - these are hard wired back to the Switch and I have several TV's and Apple TV's hard wired with CAt6 cabling all going back to the switch. 

A few days ago my system went offline - I've been onto apple support and Virgin and reconfigured etc.  But the signal from the Swtich on all the products kept dissapearng and reappearing - I unplugged a few of the products and then directly plugged the into the Airport Extreme and they are all working fine.  It looks like the Switch is creating a DHCP (??) and conflicting with the Extreme - How do i stop this from happing so it's just a dumb (?) switch. Thank you