Mac Connect to VPN (L2TP) - Can't access computers on local network

Let me start by saying I have a VPN connection setup on my Zywall 310 that works almost flawlessly with my Windows 10 machines. When I connect my Mac (running Big Sur) I can connect to the VPN no issues but I cannot access anything on the network. If I try to ping anything on the remote network it fails. I have another older Mac that can connect without issue using same setup so I'm thinking it out be something with Mac Big Sur.

I read the following and wondered if it could be apply:

Starting with iOS 14 and macOS Big Sur, IPsec supports HMAC-SHA-256 with L2TP VPN. To make sure that VPN client devices running iOS 14 and macOS Big Sur can connect to your L2TP VPN server, configure the server to truncate the output of the SHA-256 hash to 128 bits. Truncating to fewer than 128 bits will result in L2TP VPN failing to connect.

I'm not sure if this would apply to a Zywall 310 which is what I have but perhaps someone has an answer.