@makulatura,

Have you made sure that you are using the same TP-Link ID as you were previously? Please ensure that you are logged into the correct account on both the Deco Network and when you are prompted in the app for your TP-Link ID. From what it sounds like, the device is simply no longer "attached" to your ID, from something potentially like inactivity of the device on your account or a password change.

If you proceed beyond the Let's Begin Page - Is the Deco Seen in the app for setup? If there were multiple firmware updates to the device since you used it, the network might need to update first. Since you can access the WebUI, make sure that your deco is using the most recent firmware version for your model.

  @makulatura,

Hmm, you should have no issue ever reaching the WebUI, especially through a wired connection. Make sure that you are trying to log in with your TP-Link ID. If not doing this through a wired connection, you may try doing this with your satellite units unplugged so you know that you will be connecting directly to the main deco.

There are a few things that you can try before making significant changes:

Disconnect your Mobile Device from your Cellular Network and Disable any VPNs functioning on the device. (Some devices now turn on their own VPN by default). Without the cellular connection, your mobile device will be forced to communicate with the network locally rather than potentially accessing the network settings through the internet.

When connected to the Deco Wi-Fi, open the settings on your phone and disable the private addressing setting for your Deco network.

Reinstall the Deco App, making sure that the app prompts you for WLAN access or to see other devices on the network. If you are not prompted, please find the permission in your phone's privacy settings and enable the permission. Without this permission, the deco will not be seen.

You mention that you cannot access the WebUI anymore. Have you tried navigating to the interface using both the user-friendly URL and also using the IP address of the Deco? Try Connecting with a wired connection to see if you can access the login for the webui

Without access to the UI or app, this is a limited solution, but if you can gain access, you can set a different deco node as the main router and swap the nodes accordingly; this reconfiguration fixes most routing behaviors.

In case you haven't tried it, please also attempt to bring the network offline by unplugging first the satellite Decos, and then the main deco. If you leave the devices unplugged for a period of time like 5 minutes, they should renegotiate with your modem and may fix whatever hiccup your network is experiencing. It is also recommended to reboot your modem at some point in the troubleshooting process to achieve a similar effect. As much as everyone hates the work that can come with it, it may not be a bad idea to reset the network to factory defaults.

  @makulatura 

Private Addressing Can be Turned Off via Connections > Wi-Fi >Gear Icon of Current Network > View More at the bottom of the list > Change the MAC Address Type from Randomized to PhoneMAC (But this won't fix the issue, but may allow you to access the network though the deco app.

The WLAN/ Nearby Devices option should appear as an option in your phones settings under Apps > Deco > Permissions

I honestly believe that the issue is caused by having the two modems on the network. Nobody on my team has seen this in consumer applications and it is only used when you are paying for multiple IPs or an additional business line. Who is your ISP, and did they explain why they needed two modems, rather than simply running a cable to another router or access point? 

Since you have access to the WebUI now, I would recommend taking a look at the system log to see if there are any glaring errors that could be causing the behavior

  @makulatura,

I believe that on your phone, at least from the screenshot provided the setting is called full network access. Were you able to see anything in the WebUI or System Log that would indicate an issue with a setting or the configuration?