Router will not connect to Modem

[02luke08]

Recently, I bought a tp-link router model number TL-WR841N to replace my other router. However, it will not communicate with my modem. The modem is definitely functional, as I can gain internet access when directly connected to it. I have tried every solution listed on tp-link's troubleshooting webpage www.tp-link.com/us/faq-138.html yet none of them have worked. The modem is an Arris model number TM602A/100 .

 

[Ralston18]

First try another known working ethernet cable. In fact, try a couple of them if available...

Do you have the router's User Guide?

Here is a link to the User Guide:

https://tplink-manuals.org/tplink-tl-wr841n-wr841nd-user-guide/

Access the router's admin screens. Enable (if necessary) and view the logs.

Run the diagnostics as well. Most of that is presented in Section 4.16. Overall it is best to read through the manual to keep the bigger picture in mind. You may spot something else that is incorrect or mis-configured.

Very good that you went to the FAQs. However, you may need to revisit the website as you learn more or find out more about your router.

 

[02luke08]

I tried other ethernet cables and the router still did not link to the modem.
LOGS:
64 1st day 00:04:45 DHCP INFO DHCPC DHCP Service unavailable, recv no OFFER
63 1st day 00:04:42 DHCP INFO DHCPC Send DISCOVER with request ip 0 and unicast flag 1
62 1st day 00:04:40 DHCP INFO DHCPC Send DISCOVER with request ip 0 and unicast flag 1
61 1st day 00:04:36 DHCP INFO DHCPC Send DISCOVER with request ip 0 and unicast flag 0
60 1st day 00:04:34 DHCP INFO DHCPC Send DISCOVER with request ip 0 and unicast flag 0
59 1st day 00:04:32 DHCP INFO DHCPC Send DISCOVER with request ip 0 and unicast flag 0
58 1st day 00:04:15 DHCP INFO DHCPS:Recv INFORM from D4:3D:7E:9B:76:84
57 1st day 00:03:16 DHCP INFO DHCPS:Recv INFORM from 00:19😀1:39:CF:31
56 1st day 00:03:08 DHCP INFO DHCPS:Recv INFORM from D4:3D:7E:9B:76:84
55 1st day 00:02:52 DHCP INFO DHCPC DHCP Service unavailable, recv no OFFER
54 1st day 00:02:50 DHCP INFO DHCPC Send DISCOVER with request ip 0 and unicast flag 1
53 1st day 00:02:48 DHCP INFO DHCPC Send DISCOVER with request ip 0 and unicast flag 1
52 1st day 00:02:44 DHCP INFO DHCPC Send DISCOVER with request ip 0 and unicast flag 0
51 1st day 00:02:42 DHCP INFO DHCPC Send DISCOVER with request ip 0 and unicast flag 0
50 1st day 00:02:40 DHCP INFO DHCPC Send DISCOVER with request ip 0 and unicast flag 0
49 1st day 00:01:43 DHCP INFO DHCPS:Recv INFORM from 00:19😀1:39:CF:31
48 1st day 00:01:42 DHCP INFO DHCPS:Recv INFORM from D4:3D:7E:9B:76:84
47 1st day 00:01:30 DHCP INFO DHCPC DHCP Service unavailable, recv no OFFER
46 1st day 00:01:28 DHCP INFO DHCPC Send DISCOVER with request ip 0 and unicast flag 1
45 1st day 00:01:26 DHCP INFO DHCPC Send DISCOVER with request ip 0 and unicast flag 1
44 1st day 00:01:22 DHCP INFO DHCPC Send DISCOVER with request ip 0 and unicast flag 0
43 1st day 00:01:20 DHCP INFO DHCPC Send DISCOVER with request ip 0 and unicast flag 0
42 1st day 00:01:18 DHCP INFO DHCPC Send DISCOVER with request ip 0 and unicast flag 0
41 1st day 00:00:39 DHCP INFO DHCPS:Recv INFORM from 00:19😀1:39:CF:31
40 1st day 00:00:38 DHCP INFO DHCPS:Recv INFORM from D4:3D:7E:9B:76:84
39 1st day 00:00:38 DHCP INFO DHCPC DHCP Service unavailable, recv no OFFER
38 1st day 00:00:36 DHCP INFO DHCPC Send DISCOVER with request ip 0 and unicast flag 1
37 1st day 00:00:35 DHCP INFO DHCPS:Send ACK to 192.168.1.100
36 1st day 00:00:34 DHCP INFO DHCPS:Recv REQUEST from 00:19😀1:39:CF:31
35 1st day 00:00:34 DHCP INFO DHCPS:Send ACK to 192.168.1.101

DIAGNOSTICS:

Pinging 192.168.1.1 with 64 bytes of data:

Reply from 192.168.1.1: bytes=64 time=1 TTL=64 seq=1
Reply from 192.168.1.1: bytes=64 time=1 TTL=64 seq=2
Reply from 192.168.1.1: bytes=64 time=1 TTL=64 seq=3
Reply from 192.168.1.1: bytes=64 time=1 TTL=64 seq=4

Ping statistics for 192.168.1.1
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss)
Approximate round trip times in milliseconds:
Minimum = 1, Maximum = 1, Average = 1

 

[Ralston18]

The following is a link for the Arris modem's User Guide:

https://www.timewarnercable.com/content/dam/residential/pdfs/support/internet/ModemUserGuides/arris-tm602-userguide.pdf

Connections should be

ISP ---coax ---->[coax]Arris [Yellow ethernet port] --- ethernet cable ---->[WAN] TP-Link Router [LAN] --ethernet--->[LAN] PC.

See Section 2, Page 8 (17) of the TP-Link WR841n User Guide for a more comprehensive image.

As I understand the TP-Link router User Guide the router's default IP is 192.168.0.1 unless you changed it. However note in the route'rs User Guide (Section 3) that the router will change itself to 192.168.1.1. if there is a conflict with the modem.

Either way, the network adapters on your network computers should be looking for either 192.168.0.1 or the router IP you established (or the fall back if conflicted) to receive a DHCP assigned IP. (Subnet masks all being 255.255.255.0).

In the logs there are two devices attempting to communicate: MAC's ending in 39:CF:31 and 9B:76:84.

And the router sent to ACKs (Acknowledgements) devices with IP addresseses of 192.168.1.100 and 192.168.1.101

So some attempts at handshaking are taking place.

Set up the modem and then connect only the router. It may take some time (per the User Guides) for the two to establish communications.

Plug the modem in first and use the indicator lights to determine its status. Then do likewise with the router.

Take a close look at all the IPs and establish who is who with respect to the devices involved.

Suspect that it is just an IP conflict...