root@OpenWrt:/etc/ubond# ubond -c ubond0.conf -u root --debug -vvv
2021-04-05T22:45:12 [WARN/reorder] Reset
2021-04-05T22:45:12 [ DBG] absolute maximum mtu: 1444
2021-04-05T22:45:12 [INFO/config] new password set
2021-04-05T22:45:12 [INFO/config] link1 tunnel added
2021-04-05T22:45:12 [WARN/config] Enabling automatic bandwidth adjustment
2021-04-05T22:45:12 [INFO] created interface `ubond0'
root@OpenWrt:/etc/ubond# mlvpn -c ubond0.conf -u nobody --debug
2021-04-05T22:47:43 [INFO/config] new password set
2021-04-05T22:47:43 [INFO/config] link2 tunnel added
2021-04-05T22:47:43 [INFO] created interface `mlvpn0'
2021-04-05T22:47:43 [INFO] link2 bind to 100.84.95.106
2021-04-05T22:47:43 [INFO/protocol] link2 authenticated
2021-04-05T22:47:43 [INFO/protocol] link2 new connection -> redacted:31895
2021-04-05T22:47:43 [INFO] 1 tunnels up (normal mode)
2021-04-05T22:47:43 [INFO/protocol] link2 authenticated
2021-04-05T22:47:44 [INFO/rtt] link2 keepalive reached threashold, keepalive recieved 0.592486s ago
2021-04-05T22:47:44 [INFO] all tunnels are down or lossy but fallback is not available
2021-04-05T22:47:45 [INFO/rtt] link2 packet loss acceptable again: 0.000000%/31.000000%
2021-04-05T22:47:45 [INFO] 1 tunnels up (normal mode)
2021-04-05T22:47:46 [INFO/rtt] link2 keepalive reached threashold, keepalive recieved 0.599339s ago
2021-04-05T22:47:46 [INFO] all tunnels are down or lossy but fallback is not available
2021-04-05T22:47:46 [INFO/rtt] link2 packet loss acceptable again: 0.000000%/31.000000%

You can see that ubond won't bind to an IP address. No idea if it's related to the patch that changes snprintf to strncpy. (Let me also mention the fact that I ran the patched version of ubond with this change on Linux, it would bind to an IP and authenticate just fine.)