@stomko 

Thanks for the hint. Now I see a connection on my server and can reach internal servers.

But it seems, that the M8550 does not honor the setting "Allowed IPs" as the complete traffic is logged in my wireguard server. Any other hint for this? I set it to my internal network 192.168.21.1/24 so only this ip range should pass through the tunnel. Everything else should use the mobile connection of the M8550.

Also the NAT setting does not seem to change anything. Even without NAT, a client access is logged with the IP of the tunnel address of the M8550.

  @LutzB I actually prefer to route everything through WG, so I am using 0.0.0.0/0 to route all traffic. But my guess would be - perhaps try setting 192.168.21.0/24 instead - maybe TPLink does not like the way you defined it (the fact that .1 isn't actual network address, despite mask defines a network)

  @David-TP 

Thanks for the beta. I flashed it yesterday and let the device powered on this night (battery removed, powered by the the provided ac plug). There were no clients connected, so there should be no high load. This morning it was still very warm and I cannot tell you whether it was colder than with the stable firmware or not. I also noticed that the display backlight was still powered on. The screen was black, but you can still see that the backlight is powered on. I would guess, that this is the main source for the heat. I would strongly suggest to not only show a black screen in idle mode but also power off the backlight. This should also make the device last longer on batteries.

I followed the VPN tutorial but did not get any further with my problem. Whole traffic is still routed through the VPN. Maybe my use case is not covered by the implementation? I would like to connect the two networks behind my server and the M8550. I have this setup already running with two remote Fritz!Box routers. So my setup should be ok. Is the client VPN the right choice for this use case? As the M8500 dies not have a public IPv4, is has to initiate the connection to my server.

  @David-TP 

For the WireGuard VPN connection,

If M8550 is the WireGuard VPN client and  Fritz!Box is the VPN server, and the allowed IP is only set to a local Home Server behind Fritz!Box, the selected VPN Client device on the M8550 can only access this Home Server, no other external sites, such as Google/YouTube or TP-link forum.

M8550 will route all the traffic from the selected device into the VPN tunnel.

My server is a opnsense installation. The two FritzBoxes are on different locations, connecting via Wireguard and bridging their own network. Only traffic that matches the provided address range 192.168.21.0/24 passes the tunnel to the server network, not regular internet traffic. The M8550 is behaving total different and ignores the setting of "Allowed IPs".

  @David-TP 

The beta version did not resolve the temperature issue for me either. In addition, I have also observed that the backlight is now permanently on, even when the LCD is off.

I have no idea why you are claiming that you have received reports that the beta firmware has made many users happy. Here in the forum, there doesn't seem to be anyone who agrees with that.

For my VPN problems:

Today I got an mail from support. Long story short: site-to-site VPNs are not supported by the M8550.

The setting of "allowed IPs" and "NAT" in the client configuration are ignored and all traffic is NATed and pushed through the tunnel. 

For my heat problem:

Also got some mails from support. It seems that the display backlight is not turned off in all situations. If you remove the battery and power the device by USB only, backlight stays on all the time. If running on battery, backlight gets switched off if screensaver kicks in and the device stays at room temperature.

I hope this gets fixed in an upcoming firmware.