Cable Forum - Direct connection to Ubuntu does not work

Hi,

With modem in router, DHCP is working perfectly.

However, when I try put the cable directly into my PC (Ubuntu Server), it does not work

It does not get a DHCP response, yet on the router it does. I know the modem is the main MAC connected to the router, but do they filter connected devices somehow?

Modem is an old one (none superhub, but not motorola either).

Code:

c  2 19:27:57 precise dhclient: DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 18

Dec  2 19:28:15 precise dhclient: DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 15

Dec  2 19:28:30 precise dhclient: DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 15

Dec  2 19:28:45 precise dhclient: DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 8

Dec  2 19:28:53 precise dhclient: DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 16

Dec  2 19:29:09 precise dhclient: DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 15

Dec  2 19:29:24 precise dhclient: DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 19

Dec  2 19:29:43 precise dhclient: DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 8

Dec  2 19:29:51 precise dhclient: DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 9

Dec  2 19:30:00 precise dhclient: DHCPDISCOVER on eth1 to 255.255.255.255 port 67 interval 11

Dec  2 19:30:11 precise dhclient: No DHCPOFFERS received.

My /etc/network/interfaces

auto eth1
iface eth1 inet dhcp
mtu 1500
pre-up iptables-restore </etc/iptables.rules

I don't think the issue is iptables-rules, but willing to post them