Why can't my router connect to Internet?

I have UPC internet connection (chello.pl).
My router is D-Link DIR-300.
When I use provided modem to connect to the internet there is no problem. When I try to do it via router, I can't get a connection. I can log in to router and change its settings but the router does not "see" the internet. I set connection type to dynamic IP address (DHCP).

~~In diagnostic mode on WAN cable I get:~~

TxPair Short Cable at 15 meters RxPair Error at 15 meters (note: no longer an issue)

How can I establish a proper connection?

EDIT:
ISP -----[concentric cable]----- modem -----[ethernet cable]----- PC (that works)
ISP -----[concentric cable]----- modem -----[ethernet cable]----- router -----[ethernet cable or wifi]----- PC (that doesn't work)

My modem is Scientific Atlanta model EPC2203 Cable Modem/EMTA.

ipconfig /all while connected without router (sorry it's not in English)

Konfiguracja IP systemu Windows

   Nazwa hosta . . . . . . . . . . . : PPC
   Sufiks podstawowej domeny DNS . . :
   Typ węzła . . . . . . . . . . . . : Mieszany
   Routing IP włączony . . . . . . . : Nie
   Serwer WINS Proxy włączony. . . . : Nie
   Lista przeszukiwania sufiksów DNS : chello.pl

Karta bezprzewodowej sieci LAN Połączenie sieci bezprzewodowej:

   Stan nośnika . . . .  . . . . . . .: Nośnik odłączony
   Sufiks DNS konkretnego połączenia :
   Opis. . . . . . . . . . . . . . . : Atheros AR9285 Wireless Network Adapter
   Adres fizyczny. . . . . . . . . . : 00-25-D3-DC-23-9F
   DHCP włączone . . . . . . . . . . : Tak
   Autokonfiguracja włączona . . . . : Tak

Karta Ethernet Połączenie lokalne:

   Sufiks DNS konkretnego połączenia : chello.pl
   Opis. . . . . . . . . . . . . . . : Realtek PCIe GBE Family Controller
   Adres fizyczny. . . . . . . . . . : E0-CB-4E-08-CE-97
   DHCP włączone . . . . . . . . . . : Tak
   Autokonfiguracja włączona . . . . : Tak
   Adres IPv4. . . . . . . . . . . . . : 89.74.136.19(Preferowane)
   Maska podsieci. . . . . . . . . . : 255.255.252.0
   Dzierżawa uzyskana. . . . . . . . : 6 stycznia 2012 15:06:02
   Dzierżawa wygasa. . . . . . . . . : 8 stycznia 2012 12:30:16
   Brama domyślna. . . . . . . . . . : 89.74.136.1
   Serwer DHCP . . . . . . . . . . . : 62.179.2.134
   Serwery DNS . . . . . . . . . . . : 62.179.1.62
                                       62.179.1.63
   NetBIOS przez Tcpip . . . . . . . : Włączony

Status when connected via modem:

Jan Ajan

Posted 2012-01-05T15:26:58.293

Reputation: 433

You say RxPair Error at 15 meters (note: no longer an issue) - How did you solve this, that it is no issue any more? We have the same problem, and it still is the issue, that the connection via cable is quite unstable and we still get this message TxPair Short Cable at meters (whithout amount of meters!) – rubo77 – 2014-08-28T20:44:09.543

2If you want to use your router ( I assume you mean modem ) your going to have to spoof the MAC address of the provided modem. – Ramhound – 2012-01-05T15:35:54.080

I meant both. I have a modem provided by ISP and my own wireless router (D-Link DIR-300). I connect this modem to concentric cable and then my router to the modem via ethernet cable. – Jan Ajan – 2012-01-05T15:37:46.130

1Have you tried a different cable between modem and router? – RedGrittyBrick – 2012-01-05T15:54:03.853

Yes I tried. Didn't help. Those cables worked very well in scenario without router. But why both cables get TxPair Short Cable and RxPair Error ? – Jan Ajan – 2012-01-05T15:55:16.010

Did you make the cables? – horatio – 2012-01-05T16:13:59.530

Is your modem a DSL modem? – Excellll – 2012-01-05T20:13:35.993

I didn't make the cables. That is not important now. I'm not getting TxPair errors anymore. My modem is Scientific Atlanta model EPC2203 Cable Modem/EMTA. I did everything you suggested. I changet speed from auto to 100 or 10 Mbps. I restarted modem and router several times. I set router's MAC to one used previously on my PC. Nothing helped. – Jan Ajan – 2012-01-06T12:10:57.930

Answers

Have you shut down the modem and router and then restarted the modem and allow it to fully boot and then restart the router? Have see an issue whwrere modem is "bound " to the MAC of the computer at setup. Have seen this when changing routers as well. Have also seen cases in Canada where the ISP has to make a change to allow a different MAC. Sometimes waiting 24 hours without modem connected works if DHCP lease is short.

Have also seen D-Link modems that need to have the speed on the WAN port set manually. default is auto and some modems do not work well this way. On the D-link firmware I have it is on the Advanced tab and then Advanced Network. You can pick from 10Mbps, 100Mbps, 1000Mbps or Auto. Try each one and see what you get

Your router should also be able to Spoof the MAC of the computer and that may be needed if above does not work. There is a button on the Manual Internet setup page "Copy your PC's MAC Address" that makes this easy.

Dave M

Posted 2012-01-05T15:26:58.293

Reputation: 12 811

I tried shutting down and restarting everything several times without success. I'll try this speed setting. – Jan Ajan – 2012-01-05T15:45:10.203

My ISP will fail to assign a new address for as long as one hour. Makes troubleshooting difficult. – horatio – 2012-01-05T16:13:45.037

ISP's seem to be unhelpful anywhere in the world. – Dave M – 2012-01-05T19:40:41.137

Many modems will not recognize the new MAC address when you change to the router. Some will reset after some period of time, and others have to be reset manually. The can be done by cycling the power. There are modems in the U.S. that have a battery (for 911 service) which you can't power cycle. Those have a reset button on the back for this purpose.

gbarry

Posted 2012-01-05T15:26:58.293

Reputation: 694

Tried shutting down, disconnecting from power and restarting with button. Both router and modem. No success. – Jan Ajan – 2012-01-05T15:46:41.110

If you didn't follow the setup wizard, I'd suggest you try that first.

If that doesn't work then you are likely going to have to set it manually. Therefore, view your network connection on your PC while connected directly to the modem in order to get the primary and secondary DNS server IP addresses. Also, if the MTU is available make note of it.

Once you have that info, connect your router and enter the administrative software. This is done by entering the router's IP address (typically default is 192.168.0.1) in a browser. Once in there, you can setup the Internet connection manually. Below is a screen shot of that. Also, make sure you click to copy your PC's MAC address. This will allow the modem to think it is connected to your PC again.

Screen Shot

Remember to save settings before you close the window. This will restart the router.

CharlieRB

Posted 2012-01-05T15:26:58.293

Reputation: 21 303

I tried setup wizard and manual settings. Didn't help. – Jan Ajan – 2012-01-06T15:20:32.410

I ran into a problem that seemed identical to this one.

Resetting the modem, even a pinhole reset of both the modem and router, didn't solve the problem. MAC Cloning also failed.

The solution for me was to ask my ISP to change the modem to "bridge mode". Otherwise, it was giving my router a LAN ip instead of the public or WAN ip.

My modem is an Arris TG862G and my provider is TimeWarner -> Brighthouse -> Spectrum. (Name changes over the years) RoadRunner.

My router is a dlink DIR-810L

TecBrat

Posted 2012-01-05T15:26:58.293

Reputation: 139