ZTE MF 288 File Server Access over VPN denied

I am having trouble connecting to a file server at a remote location over our VPN. When connected to my home network and Internet via Telus Wifi and Fibre using a Mac I can connect to the VPN then login to the server. Switching the computer to an Internet connection via our ZTE MF 288 cellular modem, I can connect to the VPN, but access to the file server is denied. Any idea which MF 288 setting could be causing this? Something else?