This is apparently the only way to signal bugs in Zoiper, hoping someone in the dev team reads it...
- Android 5 (connected to any network, receiving y.y.y.y as network's DNS server IP)
- OpenVPN Connect 1.1.17
- Zoiper 1.51
- openvpn tunnel (layer 3 / tun, routed), server pushes DNS configuration (push "dhcp-option DNS x.x.x.x") (x.x.x.x being the IP address of the tun device on the server)
Current result / BUG:
- Zoiper sends/tries to send DNS queries to y.y.y.y (network's DNS).
- OpenVPN routing profile routes packets to y.y.y.y through the VPN
- y.y.y.y is unknown by the VPN server, thus DNS fails, thus registration is simply impossible
- Zoiper sends DNS queries to x.x.x.x (openvpn-pushed-DNS) (as do all other applications)
The problem can be reproduced as often as necessary, tcpdump on the server shows DNS queries for SIP servers sent to the wrong DNS server.
I'm happy to help with testing if necessary.