networking – USB tethered device constantly changing public IP address

I recently switched from iPhone to Android (Galaxy S10e), and use the phone hotspot as my primary internet.

I connect the phone to a gli-net mini router (https://www.gl-inet.com/products/gl-ar750s/) through USB Tether, and from that (only have ethernet enabled on the mini router) to a netgear Nighthawk R7000 router which we use for wifi in the house.

The gli-net router has a firewall rule to keep the TTL at 64 (or was it 65??) so we can continue to get unthrottled speeds.

On the netgear router I have also disabled 2g wifi, and only use 5g.

The problem we have is that our IP address on connected devices changes with each web request. So if we go to https://www.whatsmyip.org, we have a new IP address at almost every refresh.

It seems like there are a few addresses the the laptops rotate between ..*.7/9/15.

The DHCP lease time on the routers is 12 hrs.

Do you have any ideas what I should look at next?

When we connect through a vpn on the laptop (protonVPN for example), our IP address doesn’t change at every request.

It worked with the iPhone, so I’m wondering if something is going on in the android I’m not aware of? oh, also, the phone service I’m using only allows 1 hotspot connection, which Android respects. The iPhone ignored that. Do you think the issue could be caused by the phone service + android only allowing 1 device? I assumed that if I tethered to the gli-net that it would see that as my one device..