My friend has a tp-link tl-wr740n router. His PC has cable connection and it's ok all the time. Unfortunately, there is a problem with wifi connection. After restarting the router he can connect to the internet with his notebook and 2 smartphones but after several minutes wifi connection stops on all devices (except cable connected PC which is fine all the time). We tried to change wifi channel, mode, and channel width and updated the firmware but it didn't help. I thought that the router is broken but our another friend has exactly the same model. He brought it and we tested it but the result was exactly the same. What could be the problem? Should we provide more information?
I had the same issue with this router
TP link TL-WR740N / TL-WR740ND but I fixed it by upgrading to the latest firmware.
Please check your hardware version of the router if you install and upgrade other version then the router will crash and wont work.
After this go to http://192.168.0.1 and use admin/admin as username/password
Connect a network cable into the router. It doesn't have to be plugged into another device besides the router. This worked for me.