Ethernet and GSM Router

Hi, within my job i use industrial GSM routers (a GSM modem with thernet port) to connect computers on site to the internet and as far as my understanding of them, there a router with a simcard and act like any other router?

So..i have my ethernet shield on my arduino and i have set it to connect to a server i have, this works fine when i share my computers ethernet port and loop the arduino into there (so its using my internet) when i plug it into the GSM router however, it cannot make a connection, yet throws no ethernet connection errors.

in the router log though i do see this: DHCPDISCOVER(lan0) de:ad:be:ef:fe:ed info Oct 6 13:27:06 dnsmasq[782] DHCPOFFER(lan0) 192.168.104.146 de:ad:be:ef:fe:ed info Oct 6 13:27:06 dnsmasq[782] DHCPDISCOVER(lan0) de:ad:be:ef:fe:ed info Oct 6 13:27:06 dnsmasq[782] DHCPOFFER(lan0) 192.168.104.146 de:ad:be:ef:fe:ed info Oct 6 13:27:06 dnsmasq[782] DHCPREQUEST(lan0) 192.168.104.146 de:ad:be:ef:fe:ed info Oct 6 13:27:06 dnsmasq[782] DHCPACK(lan0) 192.168.104.146 de:ad:be:ef:fe:ed WIZnetEFFEED info Oct 6 13:31:23 kernel lan0: link down info Oct 6 13:31:25 kernel lan0: link up, 100Mbps, full-duplex, lpa 0x41E1 info Oct 6 13:31:30 dnsmasq[782] DHCPDISCOVER(lan0) de:ad:be:ef:fe:ed info Oct 6 13:31:30 dnsmasq[782] DHCPOFFER(lan0) 192.168.104.146 de:ad:be:ef:fe:ed info Oct 6 13:31:30 dnsmasq[782] DHCPREQUEST(lan0) 192.168.104.146 de:ad:be:ef:fe:ed info Oct 6 13:31:30 dnsmasq[782] DHCPACK(lan0) 192.168.104.146 de:ad:be:ef:fe:ed WIZnetEFFEED info Oct 6 13:32:59 kernel lan0: link down info Oct 6 13:33:02 kernel lan0: link up, 100Mbps, full-duplex, lpa 0x41E1

This repeats and repeats, i assume WIZnetEFFEED is the ethernet shield?

Does anyone know what is happeneing above and to why it wont connect?

The GSm router does work, and i can plug it into my computer and browse sites using the GSM.

Thanks Andy