I'm assuming you cannot just use the normal tethering function of your phone, right? Maybe your carrier has disabled it?
Because that is more stable and does not require an app.
And it also works fine on Linux.
If they have not disabled the phone function but they can detect that you are tethering and block traffic from the PC/router but not from the phone you can add a firewall rule to change the TTL of the packets to hide that they originated from another device.
or add this line to the "custom firewall rules" page in Luci web interface (or edit the /etc/firewall.user file if you are using commandline)
iptables -t mangle -I POSTROUTING 1 -j TTL --ttl-set 66
taken from this video where the guy is using this in his device https://www.youtube.com/watch?v=alMsu_tfZPE
also used by other people in the forums of GL-iNET routers https://forum.gl-inet.com/t/change-outgoing-ttl/2096