Obtaining IP address from DHCP

I recently upgraded my broadband service from Vodafone to a Pro II Full Fibre plan with a Ultra Hub router. The system is generally working but with one issue that I've been unable to resolve. Neither the internet radio nor the battery doorbell chime will connect to wifi. There were no such problems using the old router.

It's clear that the issue is not with the devices, since I have tried 3 radios and 2 versions of the doorbell chime, and all have failed to connect.

What the radios end up with is one of two messages. Either a simple "Failed to connect" or a more informative "Failed to obtain IP address from DHCP - limited or no connectivity".

I have tried every trick I've been able to find to fix this, including
- splitting out a separate 2.4 GHz frequency SSID because the door chime is designed only to operate on 2.4
- restarting the router devices
- tried connecting by different methods: pressing the WSP button on the router; entering the router password on the device.
- checking connections and related information: the radios show the following even though there is no connection to DHCP.
"View settings
"Active connection: WLAN is active
"MAC address: 30:58:90:4C:B3:F3
"DHCP: DHCP enable
"SSID: Vodafone28779B
"IP address: 169.254.116.151
"Subnet mask: 255.255.0.0
"Gateway address: 0.0.0.0
"Primary DNS: 0.0.0.0 "

The IP address shown does not appear to be the router's, but since the DHCP is apparently unable to give an IP address to the device, it's not clear to me where it comes from.

If anyone has any suggestions on how to fix this I'd be very grateful indeed.

The IP address is in the range 169.254.0.0/16, which is the IPv4 link-local range which configures itself, although I have only ever known trouble when addresses in that range show up. If your devices have these addresses, but previously got their IP addresses via DHCP it is a sure indication that there is no DHCP response from your router.

Go to your router and do whatever is necessary to enable DHCP over Wireless and make sure that your devices know any SSID and password required by your router.

Thanks, I'll try this

Hi I have similar system it works, but, have had problems with UtraHub and ARP Mac resolution, the router does seem to have problems in this low level area.

It other devices are get an IP Address from the router, the DHCP server appears to be running in the router.

If you can, do a quick IP Scan of your LAN, this may or may not reveal something.

FYI I have a previous router setup as an access point with theWIFI and DHCP Server enabled, there is NO Overlap of my LAN’s address space within the DHCP Address allocation table.

There is a CAT5 connection between the access point and the UltraHub.

I have a combination of WIRE and WIFI Connections with DHCP and FIXED so it does work to the appropriate standards.

Your devices for some reason are not reaching the UltraHub DHCP Server, load the Vodafone App on your phone, go to manage WIFI and turn Compatibility mode WIFI if you haven’t already done this.


Let us know current status.

Thanks for this. Last night I managed to overcome the problem by disconnecting the booster router and removing a Vodafone implanted antivirus tool. I need to experiment further with the booster to see if I can overcome the problem there, meanwhile everything seens to be functioning well enough from just the main ultra hub.

Your "booster router" needs not to be configured as a router or doing most of the things associated with a router. It needs to be quietly present at no higher than Layer 2 except for having its own IP address so you can access its config and nothing connected to the WAN port.

When you reintroduce the "booster router"

Set it to either a static ip or dhcp server off....

having two dhcp servers on the same subnet will cause problems as devices won't know which device to connect to.

So long as the DHCP Server address spaces don’t overlap it doesn’t matter, the client broadcast for a IP address goes to both and the first one back to client is used, if it’s within the previous lease time the first one back, it carries on otherwise it gets a new IP, remember servers and hosts over Ethernet communicate via MAC addresses otherwise NAT would never work, I.e. all non lan IPs have the routers MAC within the hosts ARP Table.

having 2 dhcp severs wont cause problems if they are configyred correctly its when one server in the same scope doesnt know what the otherone is doing that problems happen

In reply to a post by ultraproblems:

So long as the DHCP Server address spaces don’t overlap it doesn’t matter, the client broadcast for a IP address goes to both and the first one back to client is used

Actually, that's why it's *dangerous* to have two DHCP servers on the same subnet with overlapping pools. DHCP server 1 could give out an address to one client, but DHCP server 2 doesn't know about this, so could end up giving out the *same* address to a different client, leading to an IP address conflict

Unless you have the two DHCP servers coordinating with each other (which is difficult to set up), you need to have non-overlapping pools, e.g. DHCP server 1 has pool 192.168.1.50-149 and DHCP server 2 has 192.168.1.150-249

In reply to a post by ultraproblems:

remember servers and hosts over Ethernet communicate via MAC addresses otherwise NAT would never work, I.e. all non lan IPs have the routers MAC within the hosts ARP Table.

Non-LAN IPs don't exist in the host's ARP table at all. When you try to communicate with any non-local address (say 8.8.8.8) then the destination IP address is looked up in the host's forwarding table, which returns the default gateway. Then the default gateway is looked up in the ARP table, and the ethernet frame is encapsulated to the gateway's MAC address, i.e. the router.

Whether the router does NAT or not is unrelated to this. The host can *only* ever create ethernet frames addressed to other devices on the same LAN, and it encapsulates datagrams to the "next hop" device on the same LAN.