Are you sure you avoided using the WAN port?
If a new unit does the same, it's time to call TP Link support. Be sure the router firmware is current and the date/time is set.
To extend my school's wireless network I'm using three WAPs daisy-chained together with CAT5e cable starting from the main router. The first two in the chain are visible, connecting, and working fine but the third is not.
All three plus the main router are made by TP-Link. The first two WAPs are in fact routers set up as WAPs. I've given them static IP addresses (192.168.0.2 and 192.168.0.3), disabled DHCP, disabled Firewall, and enabled wireless security (WPA2-PSK, AES).
The last one in the chain, the one that's not working correctly, is a made-for-purpose WAP (TP-Link TL-WA901ND).
I gave it a static IP (192.168.0.4), disabled DHCP, and gave it the same wireless security settings as the other two and the main router.
The main router has a LAN IP address of 192.168.0.1, and its DHCP range is 192.168.0.100 to 192.168.0.199.
It also has the same wireless security settings as the other devices in the chain.
SSID for main router is "Unitel1", for first WAP is "Unitel2", for second WAP is "Unitel3" and third WAP is "Unitel4".
Password is same for each SSID.
Wireless channel for main router is 1, next WAP is 6, then 11, then 1 again for the final WAP in the chain, which is about 50 meters from the main router.
The problem is that the last WAP in the chain (192.168.0.4, SSID="Unitel4") is visible until I plug in the LAN cable from the previous WAP. Then after about 15 seconds the SSID disappears from the list of detected wireless networks. If I unplug the LAN cable and cycle the power, the SSID appears again.
I tried changing the channel selection to "Auto" but this didn't help.
Can anyone tell me what I might be doing wrong please?
Many thanks for any help/advice you can give.