WAN modem nat

[Gil]

Is there a convenient way to view the settings / web page of the remote 4g or Adsl modem via OpenVPN?
I can do via a Nat if I am directly connected to remote pfsense router;
However I don't always have a publicly accessible IP address on 4g.
These routers run a client to call in to the centre & I want to get to the 4g modem to see rssi details.
Perhaps SNMP?