7800N - DHCP not working on LAN

[parvaman25]

Hi,

My old router recently went bang so I replaced it with a second-hand Billion 7800N as I heard good reports about them. I have a Virgin Media cable connection so have set up router to connect to the separate Virgin Media modem over the EWAN connection. The problem I have is that I can't seem to get a connection to the internet when directly connecting my laptop to the router over wired connection. Its just being allocated a 169.x.x.x which suggests its not getting any service from DHCP to allocate an internal address. It is however working fine from the laptop over wireless connectivity and DHCP on the router allocates an address OK and I can get onto internet.
The ethernet LED light on the router works OK when plugging in cable. Have also tried swopping to different ethernet cable but same result. Have also tried every ethernet port in the back of the router. On the laptop I've tried usual IPCONFIG commands like /renew, /flushdns and /refresh but same result. I've also tried setting a static IP address but that didn't work either. Also tried disabling firewall but same result. I also have a couple of devices wired attached to the router via powerline adapters and they can't get an IP address either so I don't think its device specific
I'm just wondering whether the router could be faulty on the ethernet ports. Any way I can tell? Any suggestions on further troubleshooting?

Many thanks

[billion_fan]

Hi,

My old router recently went bang so I replaced it with a second-hand Billion 7800N as I heard good reports about them. I have a Virgin Media cable connection so have set up router to connect to the separate Virgin Media modem over the EWAN connection. The problem I have is that I can't seem to get a connection to the internet when directly connecting my laptop to the router over wired connection. Its just being allocated a 169.x.x.x which suggests its not getting any service from DHCP to allocate an internal address. It is however working fine from the laptop over wireless connectivity and DHCP on the router allocates an address OK and I can get onto internet.
The ethernet LED light on the router works OK when plugging in cable. Have also tried swopping to different ethernet cable but same result. Have also tried every ethernet port in the back of the router. On the laptop I've tried usual IPCONFIG commands like /renew, /flushdns and /refresh but same result. I've also tried setting a static IP address but that didn't work either. Also tried disabling firewall but same result. I also have a couple of devices wired attached to the router via powerline adapters and they can't get an IP address either so I don't think its device specific
I'm just wondering whether the router could be faulty on the ethernet ports. Any way I can tell? Any suggestions on further troubleshooting?

Many thanks

What firmware version are you on?

[parvaman25]

Firmware version 1.06h. Also physical port status of Ethernet is ticked (green).

[billion_fan]

Firmware version 1.06h. Also physical port status of Ethernet is ticked (green).

Its strange that Ethernet port status shows as working etc,

What colour is the Ethernet light when a device is attached?? If possible try using a giga lan device

[parvaman25]

When attached it goes green. Have tried it with giga lan device - no joy. Have also tried selecting different LAN speeds and duplex but no joy either

[billion_fan]

When attached it goes green. Have tried it with giga lan device - no joy. Have also tried selecting different LAN speeds and duplex but no joy either

Reset the unit back to factory default settings, and then try plugging your PC to the EWAN port (the EWAN port can be used as a fifth Ethernet port when in ADSL mode) if this works, it will confirm that the LAN ports 1-4 are failing.

I assume you tried a the following fixed IP address

IP address - 192.168.1.200
Subnet - 255.255.255.0
Gateway - 192.168.1.254
DNS Server - 8.8.8.8

[parvaman25]

Yep - tried those fixed IP settings with no joy.
Will do a reset tonight as suggested and plug cable from laptop directly into EWAN port.
What should I see when that happens (bearing in mind my cable modem will no longer be connected to that port).
I assume then if I do see something on EWAN port and then plug it into a LAN port and nothing happens then that will confirm a faulty LAN port.
Thanks for your help so far

[billion_fan]

Yep - tried those fixed IP settings with no joy.
Will do a reset tonight as suggested and plug cable from laptop directly into EWAN port.
What should I see when that happens (bearing in mind my cable modem will no longer be connected to that port).
I assume then if I do see something on EWAN port and then plug it into a LAN port and nothing happens then that will confirm a faulty LAN port.
Thanks for your help so far

Yes you should see the EWAN port turn amber (as it runs at 100mbps) and try and connect to the router web gui on http://192.168.1.254, that should work, then try any port 1-4

[parvaman25]

OK, reset the 7800N and plugged CAT5 ethernet cable from my laptop into EWAN port and got an amber connection OK and was assigned an internal 192.168.1.x IP address on my laptop and could log onto router. Then tried the same process by plugging the ethernet cable into LAN ports 1-4 in turn and it didn't connect. My laptop was assigned a 169.x.x.x address. Does this prove then that I have a fault on the LAN ports?

[billion_fan]

OK, reset the 7800N and plugged CAT5 ethernet cable from my laptop into EWAN port and got an amber connection OK and was assigned an internal 192.168.1.x IP address on my laptop and could log onto router. Then tried the same process by plugging the ethernet cable into LAN ports 1-4 in turn and it didn't connect. My laptop was assigned a 169.x.x.x address. Does this prove then that I have a fault on the LAN ports?

It does look like it (though I have never seen a fault like this eg ethernet light green but limited or no connectivity, and I've tested hundreds of 7800n)