FusionHub in AWS - Communicating Between EC2 Instances

I’m building a PoC for a new deployment for our assets utilizing PepVPN/FusionHub and have run into a roadblock.
I’ve got a Max BR1 Mini configured and successfully tunneled to my FusionHub inside an AWS EC2 instance. My two EC2 instances are in the same VPC and can ping each other over the 172.31.0.0/16 network. FusionHub has DHCP enabled and I can see my Max BR1 Mini modem resolving an IP (pingable via System → Ping) within the assigned range (192.168.100.0/24). I’m at a loss on how to configure AWS to allow my other EC2 instance to ping/access this device in the 192.168.100.0/24 network. My expectation was that I would access end devices over the Max BR1 Mini’s IP address via port forwarding on the cell modems (ie 192.168.100.10:502, 192.168.100.11:502 etc.). Any advice would be appreciated, thanks.