Some routers only allow so many things to be connected at one time.
That's not true. You have the entire range of your local ip scheme if you are using any wireless router.
If you are having the same issue I was, where it would see my wireless AP and try to connect, but fail then edit IP and DNS and change MTU to lowest 576.
So once it tries to connect to the AP it will fail, then at the top right tap the change settings, then scroll over to IP Address and change it from automatic to manual and enter the info below. Do the same for DNS.
If you want to know wha t DNS and gateway to use.. go to command prompt and type ipconfig /all scroll to the top and you will see the IP of your computer. If it's say 192.168.0.100 then choose something around 192.168.0.30 as most likely the higher range is reserved for DHCP. Put the gateway and DNS listed in Ipconfig.
I had to set MTU to 576 for mine to work.
The DHCP server doesn't reserve a range of ip addresses. The DHCP server provides the entire range of your ip addresses when it's enabled. Choosing 192.168.0.2 is the same as using 192.168.233.65. By manually configuring the IP address in the Wii U, you are reserving a specific IP address for the device. Essentially, the Wii U is telling your router, "No thanks, I already have an IP." There's a strong possibility that the Wii U has DHCP communication issues.
I don't know a whole lot about MTU values other than that they are the size of the individual packets being sent. 1500 is standard in virtually all networks. Changing the MTU to a lower value means both devices are processing more packets because the info is segmented up into smaller packets vs the larger capacity of a 1500 MTU value. Not sure which one means harder work for the devices.
Mine won't connect from the distance it's at from my router. The wii does. The 3ds does, even my phone does, but the wii u doesn't. Just means I need to move my router closer. (st least, that worked for me) The nice thing was that I could set up my nintendo account using just the wii u & game pad with no tv.
Sounds like you did something else for it to work.
In my case the wireless router is literally 10 feet from the Wii U. The only issue I had was related to the DHCP server.