I have just upgraded my internet to NBN FTTP/FTTB and am using a VR2100 in Australia on the Exetel network. 

1) Both the wifi and LAN drop out regularly although the internet is still active to the modem. I often need to reboot it to get it working again. 

2) Some devices can't find the 5ghz wifi. I am not able to change the channel to anything above 112 for some reason. 
 

3) I also have a RE605 extender on the network but I can't set it up on one mesh as when I click on the Advanced One Mesh tab in the modem interface it says error code 1 internal error. 

Can someone please help with some settings that I can change to make this work? Getting a bit frustrating now. All equipment is new, thinking I may need to choose a different brand.