Hello  @Riley_S , thank you for your answer.

Riley_S wrote

What is the strength of the signal, by the way? If a few packets are making it through, its possible that your RE is at the limit of the router's range. While this should only affect the RE's network, it is possible that it is the cause of the the initial setup not completing correctly. 

The strength of the signal is perfect - 3 blue LEDs on the RE. If I connect to the RE network (HomeNetwork_EXT), I can ping everything without a packet loss, the internet is fast and stable ==> the HomeNetwork_EXT is working well. The problem is only if I connect to the original HomeNetwork provided by the main router. Also here the signal strength is full, I have never had any packet loss in the HomeNetwork. Just when the RE is on. The packet loss in that case is almost 99% (yesterday 100%). But not by the usual timeout. Ping 192.168.1.1 -t says something like "General error" and doesn't even wait for the timeout of the packet. I don't think the signal strength is the problem.

In the web interface for your Range Extender, do you see any errors such as a Dynamic IP Failure?

 

I didn't notice there was any error log in the range extender interface. I will check when I get home again, if there is anything.

I have a feeling that the reason your devices are able to reconnect relatively quickly when turning off the extender is that the disappearance of the Wi-Fi makes the devices refresh their IPs with the main router. Also, it would be far more likely for errors to appear here, rather than the router logs, so take a look at they system logs here too.

 

That could be. I have tried yesterday to connect my laptop via wire to the main router. I ran something like ping www.google.com -t and let it run when the RE was on. I have the correct IP assigned by the main router, just nothing gets through. I have noticed the routing table in my laptop ("route print" in windows) is wrong when the RE is on - there is no line routing the traffic to the main router etc. As soon as I unplugged the RE, the ping -t was immediately successfull. And when I checked the routing table in the laptop, it was suddenly correct.

You may try setting a static route for a device on the main network to see if this will allow the connection to pass while the RE is connected to the network; however, the best solution is to reset the extender and reconfigure the extender to your network.

 

I was thinking to try something with the routing rules, but I am no expert on this. I just knows it exists, I can interpret, what the current routing (dynamic) table says, but never have written any routing rule myself. I could learn it and try it. However, I only have the possibility to write a static route in the main router. Don't know if it's the right place. Nevertheless, its routing rules are not passed to the clients, as I write above. And I cannot write the routing rules in all the client devices in the network. Maybe it would work for the laptop. By there are smart devices etc., where I cannot do anything. And the interface of the RE is very limited. I don't know, how better I should configure this device. When I am connected through the RE, all works well. So it is communicating well to the router. I've had a feeling it is doing "too much" in the network, like getting some communication it should not handle. Or doing something to block the main router. Can you advice me on the static routing? At least where to set it? I assume it would be like "all the traffic (0.0.0.0 mask 0.0.0.0) should go to the gateway 192.168.1.1"

I have solved the issue: I returned this piece of hardware and bought a repeater from another brand - I have set it up the same way as the TP Link Repeater and it is working perfectly. So the problem really was in the TP Link not communicating correctly with the router. My advice is to buy another brand or at least other model than TL-WA850RE.

  @buxter 

This seems to be very simular to my situation, I have an 854RE extending WiFi from an 850RE in Access point mode, as soon as the 854RE is powered up my network becomes unstable. Affecting Windows connected devices even on my Ethernet.

Tech support suggested secondary DNS values in my C7 Router which seem to fix it for a few days. But the problem is back. A non TP Link device seems an extrem fix but if it works I may have to try it? 

  @buxter 

My WA850RE worked fine for about a month, but nowI have EXACTLY the same problem as buxter describes. Thank you for the fine description, so i know it probably is something gone bad with the RE. This RE was dirt cheap, the cheapest I could find. Should apparently spent a little more on a better one.

Best regards

Same issue, disable DHCP doesn't work. 

Hi, I'm having exactly the same issues.  Has any one from TP-Link responded to this?

My returns date is fast approaching so would rather sort this out than send it back and use another brand. 

It hs been some time since I used the RE, but the reason for the trouble I got probably did not have anything to do with the RE.

My router (that is the gateway in the local net) had an IP of 10.0.0.138 and handed ot dhcp in the range 10.0.0.20 to 10.0.0.200. So the gateway in the net, 10.0.0.138, could be assigned to some local thing in the network. If that happens access to internet wil be lost.

I did the following:

- changed the IP of the router to 10.0.0.1 (this is the gateway for access to internet)

- DHCP pool for the router still at 10.0.0.20 to 10.0.0.200

- Fixed the RE to 10.0.0.2

- Made sure that RE was set to OFF for DHCP.

Since Those changes the RE worked flawlesly. Just to test again i fired up the TP-link RE and connected a cellphone to it. Runs fine. 

Make sure that dhcp on RE is set to OFF. If you must have it on, have different ranges for DHCP on the router and on the RE. If you have more than one range extender, make sure that no pools for DHCP overlab.

Best regards

  @buxter Did this ever get resolved?

I have the exact same issue with an 860RE, even wired clients are losing network as well as anything connected to the main router's SSID, I tried using the same SSID and hiding the broadcast of the main router, worked for a few mins and then had the same issue 

Have done all of the above as well, static IP, no DHCP etc

  @jesperk2 Thanks for the reply, I didn't see this and I ended up taking it back before I got the chance to try your solution.  I got a AC750 instead which was only slightly more expensive and it has been working perfectly ever since without having to make any changes.

Now I know why the 850RE is on sale everywhere lol