Access USB modem through 2 routers

this is my setup
Peplink -ethernet- Gli - USB - Huawei modem
Gli LAN port is connected to Peplink WAN port

address is 192.168.100.1 for peplink
address is 192.168.10.1 for gli
address is 192.168.1.1 for USB modem

I cannot access the USB modem interface through the peplink wifi. I think the ports are blocked. How do I open the ports to 192.168.1.1 is accessible?

Can you access 192.168.10.1 via peplink wifi?

yes I can, I just can’t access the USB modem unless I connect to the gli directly

You can connect to peplink wifi and track it with the command “traceroute 192.168.1.1”

this is not command in windows
I use ping 192.168.10.1 and get reply
I use ping 192.168.1.1 and it times out

I use tracert 192.168.10.1 and get 1 hop
I use tracert 192.168.1.1 and get my VPN IP Address, which then goes through 2 more IP Addresses
I use ping on those 2 IP address and each is 1 TTL less than the previous, the times out, both are on the cloud provider