@Clive_A as I said above, after replacing the ER605 V1 with the ER7412-M2 that upgrade went well with the existing equipment and switches. I might just try a ER605 V2 for this new build out and scrap...

@Clive_A After reading through the thread in the link you posted, it does look like exactly the same problem. So, really the only work-around I know is to add a SG2008P switch. As I explained...

@MR.S yes I have done that. As I had explained. I had VLAN 10 passing out leases to the Linux box in standalone. And I have no other switches attached.

After upgrading to ER7412-M2 I decided to repurpose this gateway and initially ran it in standalone with the management VLAN 1 at default 192.167.0.1 and a VLAN 10 at 10.10.10.1. With a separate...

Reverse SSL proxy would be a fantastic addition.