I’m a bit in the same situation, I’ve got my Linux pc tethered, but via wifi, no usb, to my android phone witch is connected on the internet using my sim card 5G. I try some different settings.
On the android phone I check ‘run on wifi’ + ‘run on metered wifi’ and the devices don’t connect. When I check ‘run on mobile data’ they connect. Then, what I find weird, with these three boxes checked, if I disable the 5G on the phone, so I don’t have any internet, Syncthing is keeping on connecting the devices.
At this point the result is ok for me, as my main goal is to use Syncthing without consuming my mobile data on the 5G, but it’s not easy to use.
So on my pc, I disabled the dynamic addressing in the settings of the device known as my phone, and affect the TCP address that is displayed when the connection work. But on the phone when I uncheck ‘run on mobile data’ the devices become disconnected.
Is there a convenient way to have Syncthing in this wifi tethering situation, with being sure that it doesn’t use mobile data ?
Here is the print of
‘ip address show’
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: enp1s0: <NO-CARRIER,BROADCAST,MULTICAST,DYNAMIC,UP> mtu 1500 qdisc fq_codel state DOWN group default qlen 1000
link/ether 8c:16:45:90:2a:f5 brd ff:ff:ff:ff:ff:ff
3: wlp2s0: <BROADCAST,MULTICAST,DYNAMIC,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
link/ether b0:fc:36:62:65:8f brd ff:ff:ff:ff:ff:ff
inet 192.168.243.56/24 brd 192.168.243.255 scope global dynamic noprefixroute wlp2s0
valid_lft 1907sec preferred_lft 1907sec
inet6 fe80::80ce:1097:d339:74ea/64 scope link noprefixroute
valid_lft forever preferred_lft forever