TL-MR6400 V5.3 is unable to establish IPSec-connection to a AVM FRITZ!Box 7490 on its own
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Hello,
I have issues with a TL-MR6400 router, which I'd like to use for VPN. The problem I have is EXACTLY the same as described here:
https://community.tp-link.com/en/home/forum/topic/99462
(TL;DR: TP-Link-Router got a private IP from the ISP, the FRITZ!Box has public one. IPSec connection simply cannot be initiated by the TP-Link-Router).
In addition to that, I was able to get a public IP for the TL-MR6400 for test purposes, but even then, there was no way to establish a VPN connection initiated by the TP-Link router. It only works, if the connection is initiated by the FRITZ!Box. I tried several Firmware versions on the TL-MR6400 without success.
I'd be pleased if someone has a solution or any other ideas to solve this issue.
Hello,
thank you very much for your reach out and support offer.
Sure!
Note that the FRITZ!Box in this case has a dynamic DNS name ("somedomain(dot)name(dot)net", whited out on the screenshot) with a public IPv4 address. The TP-Link router got a private class A IP address (10.x.x.x). The local net at the TP-Link site is set to 192.168.1.0/24; on the FRITZ!Box-site its 192.168.178.0/24.
If I use a public IP address using alternative APN credentials on the TP-Link-Router site and exchange the generic '0.0.0.0' Identifier with its public IP address, the connection works, but only when the check mark "VPN-Verbindung dauerhaft halten" ('Maintain permanent VPN-connection') on the FRITZ!Box is set. The 'Dead Peer Detection' option on the TP-Link site has no effect. I deduce from this that the connection setup initiated by the TP-Link router is not working for some reason. However, that doesn't exclude the possibility, that the FRITZ!Box simpy denies initial VPN connection initiation requests from the TP-Link router.
In the meantime, I reverted back to the Firmware available on the official support webpage. The behavior is the same.
ISP is 'Congstar', a subsidiary of 'Telekom'. Both are using the same APN credentials and infrastructure.
I cannot provide a clear conformation, as I'm unable to sniff packets along the connection Initialization, but, as I've explained above, even with a public IP addresses assigned to both sites, the 'Dead Peer Detection' doesn't appear to establish the connection on that particular setup.
For test purposes, I might able set up another VPN Gateway (Raspberry Pi) within the FRITZ!Box local network with Port Forwarding enabled and see, if it picks up any packets from the MR6400 router. Then I can confirm or exclude that the Issue is the FRITZ!Box.