"Connection timeout" on Remote User Access with OpenVPN on PepLink Balance 20X

[p.pasquali]

Hello, I apologize for the grammar, I use google translate.
I bought a PepLink Balance 20X to connect on the internet a site where there is no VDSL connectivity yet, so I'm using its built-in LTE modem waiting for a VDSL to plug into its WAN.

I inserted a Vodafone (IT) sim. LTE connectivity works great, but there is no way I can get "Remote User Access" to work with OpenVPN.

I'll explain what I did. I have only configured these minimum settings, I have not changed anything else on the PepLink:

• I have configured the PepLink as the main gateway for the 192.168.11.1 network
• I have disabled DHCP on Untagged LAN as DHCP is a server inside the network
• I inserted the Vodafone sim without customizing the settings (APN etc ..) and it connected immediately with automatic configuration
• I updated the PepLink to firmware 8.2.0 build 5141
• I activated Remote User Access of the OpenVPN type, I entered a "test" user with an 8-character password
• I downloaded the configuration file for the "Split tunnel" client from the Balance 20X
• on the server there is a ddns that constantly updates the IP of the sim
On my client, I have OpenVPN Connect installed. My client works fine, because I use it with other OpenVPN servers, I also use it to connect to another PepLink Balance 20 connected via a VDSL on its WAN, and it works great.

On this PepLink however, I try to connect on DDNS but it doesn't work! In the logs on my client I read:

• Server poll timeout, trying next remote entry …
• Connection timeout

I also tried the following tests:

• I also tried to use different protections besides UDP 1194
• I tried with TCP 1194
• I tried with L2TP mode with a preshared key, but I get the same "Connection timeout"
• I tried to connect on the public ip other than on ddns
• I tried another sim Tim (IT)
• I tried to connect also connected to the Balance 20X network in wifi, but I get "user authentication failed". This seems strange to me, I'm sure the test credentials are correct, I also recreated them.
• I tried to activate DHCP on Untagged LAN
Unfortunately I don't have another WAN to try, I don't have the VDSL yet, in which case I could have stopped the sim (even if I tried 2, from 2 different operators).

Can you tell me if I did something wrong? What could I feel? Could it be a "defect" in the PepLink Balance 20X or a defect in the firmware?
Thanks a lot to everyone!

[p.pasquali]

Hello, I'm updating this post after a long time: the problem was the "untagged LAN" as it had DHCP disabled. I created a "LAN 2" with DHCP active, and everything worked!

Now I write after some time, because for a long time OpenVPN on PepLink Balance 20X has always worked perfectly, until a few days ago. Suddenly, without having changed anything, it was no longer possible to connect from the outside. I tested multiple clients and multiple external connections, all the same result:

⏎[Mar 24, 2023, 11:26:50] Frame=512/2048/512 mssfix-ctrl=1250
⏎[Mar 24, 2023, 11:26:50] UNUSED OPTIONS
5 [resolv-retry] [infinite]
6 [nobind]
7 [persist-key]
8 [persist-tun]
10 [verb] [3]
13 [tls-client]
⏎[Mar 24, 2023, 11:26:50] EVENT: RESOLVE ⏎[Mar 24, 2023, 11:26:50] Contacting ***.***.***.***:1194 via UDP
⏎[Mar 24, 2023, 11:26:50] EVENT: WAIT ⏎[Mar 24, 2023, 11:26:50] WinCommandAgent: transmitting bypass route to ***.***.***.***
{
"host" : "***.***.***.***",
"ipv6" : false
}

⏎[Mar 24, 2023, 11:26:50] Connecting to [******.ddns.net]:1194 (***.***.***.***) via UDPv4
⏎[Mar 24, 2023, 11:27:00] Server poll timeout, trying next remote entry...
⏎[Mar 24, 2023, 11:27:00] EVENT: RECONNECTING ⏎[Mar 24, 2023, 11:27:00] EVENT: RESOLVE ⏎[Mar 24, 2023, 11:27:00] Contacting ***.***.***.***:1194 via UDP
⏎[Mar 24, 2023, 11:27:00] EVENT: WAIT ⏎[Mar 24, 2023, 11:27:00] WinCommandAgent: transmitting bypass route to ***.***.***.***
{
"host" : "***.***.***.***",
"ipv6" : false
}

⏎[Mar 24, 2023, 11:27:00] Connecting to [******.ddns.net]:1194 (***.***.***.***) via UDPv4
⏎[Mar 24, 2023, 11:27:10] Server poll timeout, trying next remote entry...
⏎[Mar 24, 2023, 11:27:10] EVENT: RECONNECTING ⏎[Mar 24, 2023, 11:27:10] EVENT: RESOLVE ⏎[Mar 24, 2023, 11:27:10] Contacting ***.***.***.***:1194 via UDP
⏎[Mar 24, 2023, 11:27:10] EVENT: WAIT ⏎[Mar 24, 2023, 11:27:10] WinCommandAgent: transmitting bypass route to ***.***.***.***
{
"host" : "***.***.***.***",
"ipv6" : false
}

⏎[Mar 24, 2023, 11:27:10] Connecting to [******.ddns.net]:1194 (***.***.***.***) via UDPv4
⏎[Mar 24, 2023, 11:27:20] Server poll timeout, trying next remote entry...
⏎[Mar 24, 2023, 11:27:20] EVENT: RECONNECTING ⏎[Mar 24, 2023, 11:27:20] EVENT: RESOLVE ⏎[Mar 24, 2023, 11:27:20] Contacting ***.***.***.***:1194 via UDP
⏎[Mar 24, 2023, 11:27:20] EVENT: WAIT ⏎[Mar 24, 2023, 11:27:20] WinCommandAgent: transmitting bypass route to ***.***.***.***
{
"host" : "***.***.***.***",
"ipv6" : false
}

⏎[Mar 24, 2023, 11:27:20] Connecting to [******.ddns.net]:1194 (***.***.***.***) via UDPv4
⏎[Mar 24, 2023, 11:27:30] Server poll timeout, trying next remote entry...
⏎[Mar 24, 2023, 11:27:30] EVENT: RECONNECTING ⏎[Mar 24, 2023, 11:27:30] EVENT: RESOLVE ⏎[Mar 24, 2023, 11:27:30] Contacting ***.***.***.***:1194 via UDP
⏎[Mar 24, 2023, 11:27:30] EVENT: WAIT ⏎[Mar 24, 2023, 11:27:30] WinCommandAgent: transmitting bypass route to ***.***.***.***
{
"host" : "***.***.***.***",
"ipv6" : false
}

⏎[Mar 24, 2023, 11:27:30] Connecting to [******.ddns.net]:1194 (***.***.***.***) via UDPv4
⏎[Mar 24, 2023, 11:27:40] Server poll timeout, trying next remote entry...
⏎[Mar 24, 2023, 11:27:40] EVENT: RECONNECTING ⏎[Mar 24, 2023, 11:27:40] EVENT: RESOLVE ⏎[Mar 24, 2023, 11:27:40] Contacting ***.***.***.***:1194 via UDP
⏎[Mar 24, 2023, 11:27:40] EVENT: WAIT ⏎[Mar 24, 2023, 11:27:40] WinCommandAgent: transmitting bypass route to ***.***.***.***
{
"host" : "***.***.***.***",
"ipv6" : false
}

⏎[Mar 24, 2023, 11:27:40] Connecting to [******.ddns.net]:1194 (***.***.***.***) via UDPv4
⏎[Mar 24, 2023, 11:27:50] EVENT: CONNECTION_TIMEOUT BYTES_OUT : 3240
PACKETS_OUT : 60
CONNECTION_TIMEOUT : 1
N_RECONNECT : 5
⏎[Mar 24, 2023, 11:27:50] EVENT: DISCONNECTED ⏎

I tried to change the port, I checked that the ISP modem has the DMZ active so as not to block any traffic to PepLink, I checked that the DDNS is regularly updated, I also tried to connect directly to the public IP , I also tried to reconfigure OpenVPN on the Peplink. I tested with a tracert that I can reach the PepLink from outside well, I can also ping. Yet there is no connection refused log in the PepLink.
On the other hand, internet browsing goes well from the internal network, crosses the PepLink, passes through the ISP's modem and goes out onto the internet perfectly.

Do you know what other ways exist to diagnose an OpenVPN timeout?

[p.pasquali]

Hello, I'm updating the post: the problem was the ISP's modem, as even if it apparently worked, after resetting it, reconfiguring the DMZ, it "magically" started working again!
Evidently, the ISP's modem is faulty, as for no reason it only blocked vpn traffic, continuing to allow all other traffic.
So no problem on the Peplink Balance 20X.