Grandstream GRP2615 Won't Connect via OpenVPN to Multi-Tenant 3CX Server

[z4cth3p4c]

Hi everyone,


I'm trying to connect a Grandstream GRP2615 to our multi-tenant 3CX setup, which is hosted on a Debian-based VPS through Hostinger. The server is running an OpenVPN instance alongside 3CX. Computers can connect to the VPN just fine using the .ovpn profile, but the Grandstream phone never establishes a VPN tunnel.


The .ovpn file has all certs and keys properly embedded using <ca>, <cert>, and <key> blocks, and it uploads to the phone successfully. The phone is set to use expert mode for OpenVPN, and it reboots correctly after applying the config, but it never receives a VPN IP.


From the phone's network status page, OpenVPN IP is blank and NAT type is shown as "Unknown NAT()". Meanwhile, the phone is on DHCP and has valid local network access. I've verified that computers can connect with the same .ovpn file, but external VPN tests show port 1194 as closed from the outside on the public IP assigned to the VPS.


I have root access to the VPS and can modify any required configs, but I'm not sure if it's something OpenVPN-side, 3CX compatibility, or a routing issue with the phone.


Any help or insight would be appreciated.

 

[KyriacosS_3CX]

Hi,

The easiest would simply be to instal an SBC. Also you really should not be running any other software on your PBX instance.
You should ask for help through Grandstream, or on openvpn forums. As you say, the phone never gets a VPN IP, so 3CX is unlikely to be the source of the problem.

Best,
K.

 

[z4cth3p4c]

Hi K.,


I appreciate your input! I'm quite familiar with using an SBC, but in this case, I was more interested in exploring the OpenVPN setup for educational purposes. I thought there might be others on the forum who’ve successfully accomplished this and could shed some light on the nuances with Grandstream phones in this context.


That said, I’ll try deploying the OpenVPN instance on a separate VM to see if that resolves the issue. I’ll update here with any findings in case it helps someone else down the line.


Thanks again,
Zach

 

[KyriacosS_3CX]

Hi,

I will be looking out for your results You never know when one might need to use a new method to deploy some phone and always good to find the solution already posted !