Is there any way to enable SNMP on the LAN side of the Yayzi supplied router?
Apologies, I thought i’d replied to this one, but apparently not. You don’t mention which router (they have issued 3 so far this year that I am aware of), if it’s the HX220, log in, click advanced, system tools, SNMP Settings and enable it 
I have the EX820v and that has no obvious setting in the GUI for SNMP.
That option is not available in the GUI. Its possible Yayzi may have disabled that setting remotely. 