The Hormann BiSecur LAN/WAN gateway only works on the LAN anymore. From the phone outside the LAN, I connect via VPN. The VPN server is set up on the router to which the gateway is connected by cable. On the phone, after connecting to the network via VPN, I can see the BiSecur gateway in the web...

. Is the IP address of the gateway specified in the configuration of this application or is there no IP address in the application and the application finds the gateway by itself ?

The app finds the gateway itself.

That is, it uses some kind of broadcast mechanism (not sure what kind). At best it could be a firewall problem, at worst it could be an L2 layer problem and therefore as it is on the same network it works. These are just guesses.

In the manual it says the web goes on port 80 and on port 4000 goes some proprietary protocol via TCP. I checked with linux nmap -sV and indeed only these two ports are used. I don't know what blocks applications outside the LAN. Maybe there is a solution to enter the phone via VPN so that the gateway does not know that the phone is outside the LAN?

. Where did you catch this traffic ? Did you do port mirroring ? To me this looks like a typical broadcast / multicast problem. Read up - I think you will understand [edit] Obviously I don't know if this is where the problem lies but if the app is looking for itself then as I wrote it must be doing it somehow (broadcast?). Unfortunately I don't know how the manufacturer solved this - it's just a guess. The solution could also be an EoIP tunnel but IoS doesn't seem to support that.

I haven't done the steps you write about, but I will look and test. For now, thank you for your replies and I hope to hear back soon with the results of your actions.

Hormann BiSecur Gateway LANWAN - no connection via VPN, only works on LAN

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iOS app likely blocked by VPN routing or discovery
#1 21639661 20 Aug 2025 13:07

malybz malybz

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iOS app likely blocked by VPN routing or discovery
Post #1 21639661 20 Aug 2025 13:07

The Hormann BiSecur LAN/WAN gateway only works on the LAN anymore.
From the phone outside the LAN, I connect via VPN.
The VPN server is set up on the router to which the gateway is connected by cable.
On the phone, after connecting to the network via VPN, I can see the BiSecur gateway in the web browser, but the BiSecur application is unable to connect to the gateway.
When I am on the LAN, the app on the phone normally detects the gateway and works fine.
What could be blocking the app from connecting to the VPN?
AI: What type of VPN is being used (e.g. OpenVPN, L2TP, PPTP) and is full tunneling or split-tunneling enabled in the VPN configuration? .
L2TP
AI: What operating system (Android/iOS) and version of the BiSecur app do you have installed on your phone?
iOS
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#2 21649071 30 Aug 2025 21:54

Anonymous Anonymous

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Post #2
21649071 30 Aug 2025 21:54

malybz wrote:
the BiSecur application is unable to connect to the gateway
.

Is the IP address of the gateway specified in the configuration of this application or is there no IP address in the application and the application finds the gateway by itself ?
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#3 21649200 31 Aug 2025 07:57

malybz malybz

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Posts: 9
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Post #3
21649200 31 Aug 2025 07:57

The app finds the gateway itself.
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#4 21649223 31 Aug 2025 08:54

Anonymous Anonymous

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Post #4
21649223 31 Aug 2025 08:54

malybz wrote:
The application finds the gateway by itself.

That is, it uses some kind of broadcast mechanism (not sure what kind). At best it could be a firewall problem, at worst it could be an L2 layer problem and therefore as it is on the same network it works.

These are just guesses.
#5 21649268 31 Aug 2025 10:14

malybz malybz

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Posts: 9
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Post #5
21649268 31 Aug 2025 10:14

In the manual it says the web goes on port 80 and on port 4000 goes some proprietary protocol via TCP. I checked with linux nmap -sV and indeed only these two ports are used. I don't know what blocks applications outside the LAN. Maybe there is a solution to enter the phone via VPN so that the gateway does not know that the phone is outside the LAN?
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Broadcast or multicast likely blocking VPN discovery
#6 21649289 31 Aug 2025 10:31

Anonymous Anonymous

Level 1

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Broadcast or multicast likely blocking VPN discovery
Post #6 21649289 31 Aug 2025 10:31

malybz wrote:
I checked with linux nmap -sV it indeed only uses these two ports
.

Where did you catch this traffic ? Did you do port mirroring ?

To me this looks like a typical broadcast / multicast problem.

Read up - I think you will understand

https://community.ui.com/questions/L2TP-IPsec...ulticast/da848391-a38b-4f14-a9c7-07844b18d8d1

[edit]
Obviously I don't know if this is where the problem lies but if the app is looking for itself then as I wrote it must be doing it somehow (broadcast?). Unfortunately I don't know how the manufacturer solved this - it's just a guess.

The solution could also be an EoIP tunnel but IoS doesn't seem to support that.
#7 21649471 31 Aug 2025 14:10

malybz malybz

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Posts: 9
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Post #7
21649471 31 Aug 2025 14:10

I haven't done the steps you write about, but I will look and test. For now, thank you for your replies and I hope to hear back soon with the results of your actions.
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Topic summary

The Hormann BiSecur LAN/WAN gateway works normally on the local LAN, but the BiSecur iOS app cannot connect when the phone is outside the LAN and connected through an L2TP VPN on the router. The gateway is visible in a web browser over VPN, but the app discovers the gateway automatically and fails to connect, suggesting a broadcast or multicast discovery issue rather than a simple IP reachability problem. The gateway uses HTTP on port 80 and a proprietary TCP protocol on port 4000. Possible causes discussed include firewall filtering, blocked broadcast/multicast traffic across the VPN, or an L2-layer limitation; a tunnel solution such as EoIP was mentioned, but iOS does not appear to support it.
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Hormann BiSecur Gateway LANWAN - no connection via VPN, only works on LAN

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