USB network sharing with ipv6

Hello,

I run a pinephone with latest mobian.

When I connect my pinephone to my debian laptop with the USB cable, the laptop detects it as a wired internet connexion and gets assigned an ipv4 address (10.66.0.xxx).

Given that my pinephone is connected by WWAN and that mobile data is activated, I thought it was enough to access internet from my laptop through the pinephone.

However, it does not work. Digging a little, I found that the WWAN address of my pinephone is ipv6 only. I do not see an ipv4 address for the WWAN interface with ifconfig. Also, route only gives the default route for 10.66.xxx.xxx addresses (through the USB interface). But if I ask route -6, there I find all relevant routes for WWAN.

If I understand well my problem, it does not work because the USB tethering is configured only in ipv4 and the WWAN is configured only in ipv6. Am I correct ? Can I change the WWAN settings to get an ipv4 address too ? or change the USB tethering configuration to allow for ipv6 ?

Regards