WA850RE has no V2? Double check your model number...
Upgrade the latest firmware if there is one...
When internet access lost, how about status of all lights on the range extender?

Yes sorry it is v1 only. The signal lights (2 lit up i.e.60%) keep blinking, but they do that a lot even when the internet is working properly
Appreciate your help :)
Thanks

You got only 2 signal lights?
If so, you should place the extender closer to the main router and ensure you get at lease three signal lights to ensure a stable connection.
By the way, check the firmware version of status page of WA850RE. Upgrade the latest firmware.

I am having this same issue and I have upgraded the firmware. Have 3-4 "bars". Takes quite a while to access the internet wirelessly with the extender in place. Sometimes the connection drops. A few times I haven't been able to connect at all. I also have an Airport.

Airport express? Provide a simple topology pls.
Did you try wired connection to WA850RE?
When connection drops, lights are still normal? How did you make it work again?

Hello,

I have the WA850RE v1 as well. I am also having this exact same issue.

For almost a month when I first got the range extender, everything has been working fine. I had constant connectivity and speeds were great, finally, on my side of the house. Had 2+ MB/s download speeds which is fantastic for me.

Lately though, the wifi has been slower and more intermittent.
At first, I thought the USB ports on my mobo were dying because I have a wireless adapter for my desktop. But after some troubleshooting I ruled this out.
Second, I thought it was an issue between my adapter and the range extender which i ruled out.
Finally, I noticed the other day whenever the speeds drop or the internet goes out the Wireless Signal bars on the Range extender are flashing. After about 2 mins or so, they resume solid and everything is "alright". Ever since this issue began the speeds have never really been the same as when I first bought it. I have the extender located halfway from router to my computer and it has constant 3-4 bars of signal.

Hope someone can help. If not, guess I'll just have to return it or something.

Update: Called TP-Link tech support. Was directed to tp-link.us for the US site and there was another firmware update available.
http://www.tp-link.us/download/TL-WA850RE_V1.html#Firmware
I did the update and am still having some problems but this may help someone else.

Also noticed my router firmware is way out of date.... going to try upgrading that now to see if the problems go away

Same problem here. Had been using it for about 3-4 months and it worked perfectly fine even with 2 bars. I was plugging it in to my computer directly, and was getting about 30 ping in my games, and my download speed didn't really matter because my ISP doesn't provide good download speed anyway. Now I'm constantly fighting with it to work, and sometimes it does, but usually doesn't. I've reset it multiple times, but it only lasts about 15-20 minutes before the lights start flashing and it starts disconnecting and reconnecting (which it also shows happening on the repeater's webpage). I just updated the firmware and no luck with that.

If anybody has an answer it would be greatly appreciated!

What's the current firmware version of your range extender?
To ensure a stable connection, at least three signal lights on the range extender should be on . How about yours?
When connection drops, your router is still working? Any clients are connecting to the main router directly all the time?

Firmware: 3.14.8 Build 140826 Rel.63335n

I'm getting between 2-3 bars, not to mention 2 bars has always worked completely fine. There is no change in my router's behavior. Everything is the same except the range extender.

Reset and reconfigure it. Place the range extener closer to the router and ensure you get at least three signal lights.
If the problem continues, get a replacement under warranty.