I have this scenario:
1 lan office with:

1 classic fastweb router
and 3 client PCs on the LAN

I have some Windows client PCs
which must be able to access the local network
from outside (internet)

I got an er605 to use as a vpn server

I wanted to insert it into the office LAN without having to cascade it with the router

I was thinking of carrying out port forwarding in the router of the ports relating to the VPN service I need

and turn them to er605

it's possible ?

can someone help me ?

Thank you