This is a shot in the dark but maybe someone can help...  I recently moved to a rural location and until my Starlink kit delivers in a few weeks, our family is relying on cellular 4G LTE for internet.  I bought one of those unlimited, unthrottled [presumably] plans (uses Verizon network/bands) and a cheap phone to host the sim card.

However, the phone/plan has a limitation of only one device connecting to the phone's hotspot at a time.  This makes for a major inconvenience when trying to connect multiple devices (even just sequentially as per the TOS); for example, to transfer my "connected device" from the family room Fire TV stick to the bedroom Fire TV, I have to unplug the family room Fire TV usb cable, so it releases its hold on the phone's hotspot, which I can then connect the bedroom TV to.  There are other inconveniences, such as not being able to connect a phone to the Roomba via the wifi to program it.

I have a TP-Link Deco X60 network (802.11ax mesh) that I brought over from the old place.  The mesh network works great, and I'd like to bridge my phone's cellular to the mesh devices.  I tried one of those USB-C to ethernet adapters (with a separate power pass-through) to connect the phone to one of the mesh devices, with no result.  I don't know if that was a phone issue, an adapter issue, or a Deco issue.

However, I can successfully USB tether my phone to my PC for an internet connection.  So my thought is to use my Mint PC as a bridge for the time being (see picture).  There's been at least one Mint community forum discussion on this (which I can't find now); I tried following those instructions but no result.  Note that I do not have any wifi capability on my PC (I tried an 802.11ax dongle a few months back but the support for those just isn't there yet on Linux - or at least wasn't when I tried it); previously I was connecting one of my mesh devices to the Fios modem, and using another mesh antenna as my internet gateway for the PC.  Now I want to go the other direction.

I suspect that there is some setting in the PC ethernet port connection settings that I'm not setting correctly to get this working.  Can anyone give me pointers?

I guess the other option is to purchase a cellular modem/router, and then connect my mesh network to that... but not sure if my SIM card will work in it?  I suppose I could always just try and return the modem/router if it doesn't work.  But it seems like there should be a solution bridging over my PC here, without buying something additional.