I have a 4G router (Huawei e5172) with one LAN port (DHCP enabled). I need to connect 3 PCs and 1 wireless access point to this router via Ethernet so I got a 5-port Ethernet switch and connected it to the 4G router, and the 4 devices with Ethernet cables.

The connection works when I plug the 4G router directly to one of the PCs, but the problem is that I'm not getting any connectivity on any of the devices. I keep getting the following message "Can't resolve controller DNS" on the access point.

I'm not too savvy with networks, is there anything wrong I'm doing? How can I achieve connecting these devices to the 4G router via Ethernet cables?

Your help is much appreciated!


There are quite a lot of things to check:-

  • Are you using the correct uplink port on the switch to connect to the router?
  • Most Ethernet switches have LEDs to show connectivity: are these lighting?
  • Are you using straight, not crossed cables (though you may need a crossed cable for the access point)?
  • Leave the wireless access point disconnected initially, as if wrongly configured it may have its own DHCP server competing with that on the router.
  • Compare the PC's IP configuration when plugged into the router and into the switch: both should have the same subnet address (typically 192.168.N.x - the first three numbers should be the same, but the x may vary); the DNS server should be the same (typically 192.168.N.1).
  • If plugging in the access point stops the other PCs from working, and the switch LED shows a valid connection, then you will need to follow the AP configuration instructions to set it up correctly.
  • Thanks for the help. To answer these points: The switch's manual states that "all ports on the switch support auto-MDI/MDI-X functionality, so crossover cables and uplink ports are not needed for connections to PCs, routers, hubs, additional switches or other devices." Lights are all green and blinking. I'm using straight cables all throughout. I've tried connecting only one PC to the switch and the LAN shows no connectivity (yellow triangle) on the PC. The gateway IP is and the PC's IP is I'm not sure what other tests I can do to pinpoint the problem further. – Nino Kay Jul 13 '14 at 12:35
  • That all looks OK. Is there any difference in IP settings when directly connected to the router? – AFH Jul 13 '14 at 12:42
  • No they're the same when I do cmd > ipconfig /all – Nino Kay Jul 13 '14 at 12:47
  • What is the DNS setting on the PC connected through the switch? Can you ping to – zelanix Jul 13 '14 at 12:49
  • In that case I can see no reason that they would not be working. Try Repair on the internet connection when connected through the switch, and note any error messages. After that I am running out of ideas. – AFH Jul 13 '14 at 13:04

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