Sounds like compatibility issue, you may try to change some settings on the TL-WR840N, such as wifi channel

I basically have the same problem.
Model : TL-WR940N
Firmware Version: 3.16.9 Build 161107 Rel.69553n
Hardware Version: WR940N v3 00000000

I do know that this router commonly drops the connection with a MacBookPro 4,1, Boot ROM Version: MBP41.00C1.B03. Running OS 10.11.6, but it was dropping the connection before upgrading to El Capitan. The WiFi system info is below. I have two other MBPs, an iPhone 6, LG 4 cell phone, Panasonic BlueRay Player, Samsung TV, Yamaha Reciever, Yamaha WiFi speaker, PixStar photo frame also linked to this router with no problem that I am aware of. Note this router is set up as merely an access point, i.e. its DHCP server is turned off, it is connected via Cat 5 cable to the router for the network. Just now it dropped the connection. I tried to reconnect and after a while it says it can not connect and do I want to run diagnostics (which don't help). I turned on and connected the Samsung TV to YouTube, then the MBP connected just fine. Also rebooting this TP-Link unit and the MBP connects just fine. I notice (see below) that when the MBP can not connect, it thinks the TP-LINK is using channel 10,-1. I have not had any trouble connecting this MBP to other WiFi access points. Any other info I can provide please just ask.


WiFi info from system information
Software Versions:
CoreWLAN: 11.0 (1101.20)
CoreWLANKit: 11.0 (1101.20)
Menu Extra: 11.0 (1121.34.2)
System Information: 12.0 (1100.2)
IO80211 Family: 11.1 (1110.26)
Diagnostics: 5.1 (510.88)
AirPort Utility: 6.3.6 (636.5)
Interfaces:
en1:
Card Type: AirPort Extreme (0x14E4, 0x8C)
Firmware Version: Broadcom BCM43xx 1.0 (5.10.131.36.16)
MAC Address: 00:1f:5b:d0:b2:eb
Locale: FCC
Country Code: US
Supported PHY Modes: 802.11 a/b/g/n
Supported Channels: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 36, 40, 44, 48, 52, 56, 60, 64, 100, 104, 108, 112, 116, 120, 124, 128, 132, 136, 140, 149, 153, 157, 161, 165
Wake On Wireless: Supported
AirDrop: Supported
Status: Connected


Current Network Information:
TP-LINK_A2CC:
PHY Mode: 802.11n
BSSID: 60:e3:27:fb:a2:cc
Channel: 10
Country Code: US
Network Type: Infrastructure
Security: WPA2 Personal
Signal / Noise: -51 dBm / -86 dBm
Transmit Rate: 130
MCS Index: 15


when not working:
TP-LINK_A2CC:
PHY Mode: 802.11n
BSSID: 60:e3:27:fb:a2:cc
Channel: 10,-1
Network Type: Infrastructure
Security: WPA2 Personal
Signal / Noise: -54 dBm / -92 dBm

when wifi stops, can you still get internet from 940N by cable?

After suggestion above, I set the WiFi Channel from 'auto' to 1 (after surveying other channels being used by other WiFi units of neighbors). This seems to have helped, I don't remember a WiFi drop since then.

I've tried to change the channel (1, 6, 7, 11), but the problem persists.

uutommi wrote

when wifi stops, can you still get internet from 940N by cable?

In my case, with the TL-WR840N, I didn't check the cable connection.

uutommi wrote

Sounds like compatibility issue, you may try to change some settings on the TL-WR840N, such as wifi channel

I've tried to change the channel (1, 6, 7, 11) but the problem persists.

As I couldn't manage to restart the router every time the connection dropped, I've ended up buying another one (TP-Link Archer C8).

With the new router, everything seems to be working well.

Hi All,

I am facing the same issue. I have recently purchased a dell inspiron laptop. It has Qualcomm QCA61x4A 802.11 a wireless adapter.
When I connect wifi with TP link 841 N router, after 2-3 mins it gets disconnected. And all the gadgets also gets disconnected after that, and ultimately Ihave to restart the router again.

Could anyone please help me in that.

Thanks in advance.

Unfortunatelly I don't believe it will work properly, unless TP-Link provides a new firmware to fix this behaviour.

Did you check if is there any new firmware version for your model?

I've abandoned my TL-WR840N when I bought the Archer C8. Since then I didn't experienced this issue anymore.