LAN Network printer Not showing up in network when T-Mobile is ISP.

I have a Toshiba network printer in my small office. It does not have WiFi, it is cable-connected. It does not appear in my network places when T-Mobile is the ISP (via TMO-G4SE). However, under the same setup, it appears in the same network when i switch ISP to Comcast. Both ways, all devices are wired the same. I have a Network Drive (NAS) on the same network and it shows up regardless of ISP (no switching wires or remapping the network drive)… why is the Toshiba (e-Studio 357) not showing up on the network when T-Mobile is the ISP? Super frustrating… not a good introduction to T-Mobile as an alternative to Comcast.