@taus4u 

Hello, can we try to confirm some details about the disconnect issue you encountered with the C6 router, then we can try to fix it?
1. Only 1 Android phone has this disconnect issue? How about other wireless devices, such as laptop or other phones, are they working fine? If all the other devices are connecting to the network fine, you may need to check the settings on the Android phone itself, or confirm if the phone system needs to be updated.
2. If this happens on all the wireless devices, please check again if the issue happens on the devices connect to the 2.4G or 5G network, you can try to run a Wi-Fi analyzer to review the channels in the network, choose a clear channel, and change the channel width to 20MHz for the 2.4G, and change it to 40MHz for the 5G, reboot the router and confirm.
3. Please confirm how often does this disconnect issue happen, and how did you recover the connection? Is there any special activity that may cause the disconnect/drop out, such as high loading or downloading? How many devices are connected to the router at the same time? Try to disconnect some of them to verify if the connectivity is stable.

@taus4u 

You can try the beta firmware we provided here, which is marked as the Recommended Solution, then disable the Onemesh on the router:

https://community.tp-link.com/en/home/forum/topic/207232