Thank you for all of this information! I also do van RVing and use a combination of carriers/connections. I did a fair amount of reading on Multipath TCP as it was new to me. What I've found seems to be fairly opaque and it doesn't seem to be highly implemented. Some notes/questions:

* Every device and endpoint that it's used on needs to support it. My PCs, mobile devices, router, etc. all need to have it enabled and configured. This makes me question if every other layer 4 router in-between you and the endpoint also need to support it. * Endpoints that you're connecting to need to support it. It doesn't seem to be widely deployed. https://mptcp.io/ * OpenWRT's implementation doesn't seem well supported and the kernel that's needed for it is really old. * In your Zoom example, they'd need to support it server side (I don't see anything public stating that they do, but a packet capture would verify.) Also, a lot of that sort of real time traffic is UDP or QUIC (I don't know if Zoom is.)