This is exactly the issue we have been experiencing. Thank you PTME and newtecky for explaining what’s going on.

We already have a Sonicwall in place but with our MIPU connected directly to the ISP’s modem. Ideally I would figure out how to configure the Sonicwall, but I’ll invest in the ZyXEL router if needed.

Newtecky, if you could PM me the ZyXEL configuration steps, I would be very grateful. If anyone has the steps for a Sonicwall, that would be a bonus.

Thanks everyone, looking forward to getting this solved.