i would like to buy a USG and integrate it to my network but i would like to keep my EdgeRouter Lite.
Now my question:
Where i have to switch on or off the DHCP-Server for my network?
Or are two DHCP-Servers are ok?
I suppose my first question would be why do you want two routers? But assuming you have a perfectly valid reason (i.e. you have something else connected to the EdgeRouter, not just the USG), then so long as the two routers serve different IP address ranges (i.e. there is no overlap in the address ranges they can serve) then you can leave DHCP on both.
Two routers because i don´t know how to setup L2TP/IPSec on the USG, on my Edgerouter L2TP/IPSec is running fine and i can connect with my ios device to my homenetwork.
Maybe someone has a instruction for beginners with pictures
Tuesday - last edited Tuesday
Why do you want the USG when you already have an EdgeRouter? It sounds like you want the USG instead of the EdgeRouter, but that you can't get rid of the EdgeRouter b/c you don't know how to setup VPN on USG.
Again, what's the purpose for trying to replace the EdgeRouter with the USG?
In your diagram, having DHCP on the EdgeRouter will just end up assigning a dynamic IP to your USG. Your USG's DHCP server will receive the DHCP broadcast requests from clients connected to the switch.