ajones wrote Potentially 15 devices, but this is happening with 2. Not tried 1. I can't see a limit specified in the configuration for number of wireless clients, nor would I expect to hit such a...

Sorry I'm not so sure whether there is any chance to change to a longer timeout or not, it seems there is no information about that on the router's web interface...Maybe we just cannot do that...

How about disabling the connection after you set up the TL-WR1043ND and renew the IP address on the devices? sometimes the clients may keep the original IP addresses including the default gateway and...

Is it possible that the 3G takes a long time to connect so that the router mistakenly judge that the connection failed, then it failovers to WAN?

As to the desktop, if you connect it to the modem directly, is there any problem? and for the smartphone, what I can think about is the IP address, is it obtained from the router? what is it?

How about changing the channel to a fixed number such as 1, 6 ,11 ect. on TD-W8968?