ER8411 - Heartbeat lost all few minutes
@MR.S Okay, good point will try that, I actually have two sides, but since the external side is anyways connected over a VPN with a DynDNS address that's fine not having there an address.
The weird thing is.. when I turned the controller off and on for like 15 hours and then it worked for almost 3 hours fine, but then the loop came back, even for the fact I didn't change anything. 
For me it wouldn't matter if the router does that even every 2 minutes.. problem is just when the router tries to reconfigure after the adoption process, it disconnects me from the internet and reconnects me.
Not sure since I'm planing to get the OC220 when it is available here in Germany (hopefully soon), it will hopefully work better.. until now the onliest solution is turning off the controller. The turning off of device management didn't change something, 2 minutes later heartbeat lost.
since it happens when the router configures so I was wondering if it could be device management causing problems. I have an ER8411 and haven't had the same problem as you have. I run the controller on an old Windows PC, I have controllers on raspberry pi with other Omada routers they have also worked fine. I don't really know what your problem is but you should get TP-Link support to look at your configuration, I suspect there may be something with the configuration somewhere.
but one last suggestion, if you used a name on device management then it is saved in the config for the different devices, try to create the same name on LAN DNS that points to the local IP on the controller. that way you override any WAN IP that is used on the internet. in device view you can activate controller connection IP, if it shows WAN IP then it will be wrong when you have the controller locally.
As you can see here, 192.168.30.1 is connected to the controller, that's correct since the controller is on this network
At the remote site, it is the WAN IP of the remote site that is connected to the controller.
