VPN server doesn't work if the machine is connected via lan and wifi

[ersonp]

Describe the bug
The app vpn-server doesn't start if the machine it is running on is has a plan connection as well as wifi. It will work if the machine is connected to either one.

Environment information:

• OS: e.g. Linux
• Platform: Linux 5.13.0-39-generic x86_64

Steps to Reproduce
Steps to reproduce the behavior:

1. Connect the machine to internet via lan
2. Connect to a wifi router
3. Start visor sudo ./skywire-visor -c skywire-config.json
4. Start the vpn-server from the hypervisor UI
5. See error

Actual behavior

[2022-04-06T18:02:38+05:30] INFO [proc_manager]: Accepted proc conn. hello="{"proc_key":"e78744fae76d4c1f9a64eea315749c7e"}" remote=127.0.0.1:39642
[2022-04-06T18:02:38+05:30] INFO [proc:vpn-server:e78744fae76d4c1f9a64eea315749c7e]: Associated and serving proc conn.
[2022-04-06T18:02:39+05:30] INFO [proc:vpn-server:e78744fae76d4c1f9a64eea315749c7e]: Request processed. _elapsed="920.254µs" _method="Listen" _received="6:02PM" input=038a33fc20b568b3e40f0bba1ab4ebd9eba938e33eb1d0904ccad1320911be7643:44 output=0xc002b1829e
[2022-04-06T18:02:39+05:30] INFO (STDERR) [proc:vpn-server:e78744fae76d4c1f9a64eea315749c7e]: time="2022-04-06T18:02:39+05:30" level=info msg="Got app listener, bound to 44"
[2022-04-06T18:02:39+05:30] INFO (STDOUT) [proc:vpn-server:e78744fae76d4c1f9a64eea315749c7e]: net.ipv4.ip_forward = 1
[2022-04-06T18:02:39+05:30] INFO (STDERR) [proc:vpn-server:e78744fae76d4c1f9a64eea315749c7e]: time="2022-04-06T18:02:39+05:30" level=info msg="Got default network interface: enp4s0\nwlp5s0"
[2022-04-06T18:02:39+05:30] INFO [proc:vpn-server:e78744fae76d4c1f9a64eea315749c7e]: Request processed. _elapsed="7.844µs" _method="CloseConn" _received="6:02PM" input=0xc0028f4c98
[2022-04-06T18:02:39+05:30] INFO (STDOUT) [proc:vpn-server:e78744fae76d4c1f9a64eea315749c7e]: net.ipv6.conf.all.forwarding = 1
[2022-04-06T18:02:39+05:30] INFO (STDERR) [proc:vpn-server:e78744fae76d4c1f9a64eea315749c7e]: time="2022-04-06T18:02:39+05:30" level=info msg="Got IPs of interface enp4s0\nwlp5s0: []"
[2022-04-06T18:02:39+05:30] INFO (STDOUT) [proc:vpn-server:e78744fae76d4c1f9a64eea315749c7e]: net.ipv6.conf.all.forwarding = 1
[2022-04-06T18:02:39+05:30] INFO (STDERR) [proc:vpn-server:e78744fae76d4c1f9a64eea315749c7e]: time="2022-04-06T18:02:39+05:30" level=info msg="Old IP forwarding values:"
[2022-04-06T18:02:39+05:30] INFO (STDOUT) [proc:vpn-server:e78744fae76d4c1f9a64eea315749c7e]: net.ipv4.ip_forward = 1
[2022-04-06T18:02:39+05:30] INFO (STDERR) [proc:vpn-server:e78744fae76d4c1f9a64eea315749c7e]: time="2022-04-06T18:02:39+05:30" level=info msg="IPv4: 1, IPv6: 1"
[2022-04-06T18:02:39+05:30] INFO (STDERR) [proc:vpn-server:e78744fae76d4c1f9a64eea315749c7e]: time="2022-04-06T18:02:39+05:30" level=info msg="Old iptables forward policy: ACCEPT"
[2022-04-06T18:02:39+05:30] INFO (STDERR) [proc:vpn-server:e78744fae76d4c1f9a64eea315749c7e]: time="2022-04-06T18:02:39+05:30" level=info msg="Set IPv4 forwarding = 1"
[2022-04-06T18:02:39+05:30] INFO (STDERR) [proc:vpn-server:e78744fae76d4c1f9a64eea315749c7e]: time="2022-04-06T18:02:39+05:30" level=info msg="Set IPv6 forwarding = 1"
[2022-04-06T18:02:39+05:30] INFO (STDERR) [proc:vpn-server:e78744fae76d4c1f9a64eea315749c7e]: sh: 2: wlp5s0: not found
[2022-04-06T18:02:39+05:30] INFO (STDERR) [proc:vpn-server:e78744fae76d4c1f9a64eea315749c7e]: time="2022-04-06T18:02:39+05:30" level=info msg="Set IPv6 forwarding = 1"
[2022-04-06T18:02:39+05:30] INFO (STDERR) [proc:vpn-server:e78744fae76d4c1f9a64eea315749c7e]: time="2022-04-06T18:02:39+05:30" level=info msg="Set IPv4 forwarding = 1"
[2022-04-06T18:02:39+05:30] INFO (STDERR) [proc:vpn-server:e78744fae76d4c1f9a64eea315749c7e]: time="2022-04-06T18:02:39+05:30" level=error msg="Error serving" error="error enabling IP masquerading for enp4s0\nwlp5s0: error running command \"sh -c iptables -t nat -A POSTROUTING -o enp4s0\nwlp5s0 -j MASQUERADE\": exit status 127: sh: 2: wlp5s0: not found\n"