@Birillo 

Can you provide a more detailed description, such as a diagram of the network topology you are using? Under the same topology, you were able to implement device adoption before, right?

Have you confirmed that the Controller and the device to be adopted can access the Internet normally?

Maybe this link will help you：

How to Manage Omada Devices at Different Sites Using Omada SDN Controller via VPN (Controller 5.0 or Above) | TP-Link

 Hi @Md-Ripon3 

The diagram is simple and shown below.
 

This has been working for at least a couple of years without any issue.
TBH all started after a few days from the upgrade of the router to 1.3.0.

The connection to internet is working perfectly on both sites.

From the location A I can reach any device on location B, including the ER605 (that of course shows just the screen that it is managed by Omada.
I also successfully connected via ssh but it seems to not be so useful.

From location B I can reach any device on location A.

I tried to restart all the devices on both sides and the VPN is reestablished without problems but the ER605 continues to appear as disconnected on location B.

I also tried to configure option 138 on the DHCP (I tried with the internal address and external one but nothing happens. Not sure if I am using/configuring it correctly.
NAT on location A is configured to redirect the ports used by Omada to the controller.

Note that all the TP-link devices are upgraded to the latest versions

Thank you for your help
 

  Hi @Tedd404 

please see my previous post of a few minutes ago.

As explained there, I tried to configure the option 138 on DHCP. I tried with both the internal and external addresses. But nothing happens. 
I am not sure if because of the fact that the ER605 is disconnected, the DHCP changes are not applied to the remote router.

Thank you

  @Tedd404 

this is constantly disconnected since 10th July.
It happened a few days after the upgrade.
 

I created the VPN in Omada using L2TP and Network Extension Mode follwing recommendations fron tp-link support. This worked very well in my case instead of the ipsec site2site.

I put the wan address of site A in the site B DHCP configuration. But not sure if it has any effect considering that the ER605 in site B is disconnected from the controller.

The VPN is constantly active and internet in both sites is stable. I have no disconnections.
I should get notifications from site B if it drops.
 

Logs are not helping.
Nothing from site B.

  Hi @Clive_A 

The reason why I went for the L2TP option is that originally site B did not have a public IP. 
This has changed a couple of years ago, but I did not see a valid reason to switch to ipsec since the VPN ws working great.

In which way ipsec could help with my situation?

BTW I cannot reconfigure the VPN until when the router reconnect to the controller ...I assume!
 

I also cannot downgrade the ER605 since it is currently located in another country with nobody onsite. The only think I can do is connect via VPN.

Hi @Clive_A 

thanks a lot for your help!

The device is in this status since July!

It never reconnected to the controller ....except for the VPN that continue working as usual.

FYI ssh is enabled on the ER605 ..but for what I saw there is no useful command that could help.

I can reach the web interface ..but it says that it is managed by Omada.

In the same network I can reach a small linux device (arm64). I tried to run there the Discovery utility but without any luck. 
I tried different JRE distribution and JavaFX libraries but I have not been able to successfully run the utility. It crashes as soon it starts.