Issue with ICMP and Trace routes

[Murtaza12]

Hi everyone, I'm new here
Having an issue with a new modem and the inability to do trace routes.

I have an ADSL2+ connection at my house, the modem provided by the ISP was trash, so I ordered a TP-Link TD-8840T ADSL2+ Modem/Router (non-Wireless).

Before the setup was as below:

ISP modem (D-Link 2750U) - TP Link WDR3500 Router (connected through blue WAN port). I was able to perform trace routes, without packet loss and timing out.

Ever since I bought the new TP Link modem and connected it to my TP Link router, through the blue WAN port, I can't perform trace routes. After hopping on the modem, it times out after that on every hop.

here's a copy:

2 ms 2 ms 2 ms 192.168.1.1
* * * Request timed out.
* * * Request timed out.
* * * Request timed out.

And it keeps on going like this.

Some people said it had something to do with Double NAT, so I used my router as an Access Point and connected it to the modem through the yellow LAN port, however still can't perform trace routes. Weirdest part is, if I connect my laptop DIRECTLY to the modem through LAN cable, I still can't perform trace routes.

Really confused. Would greatly appreciate if someone could help out here.

Thanks

 

[Deepcuts]

When connecting your laptop directly to the modem, do you have to setup your connection on the laptop, like a PPPoE, or it connects automatically via DHCP?
I guess what I really want to ask is if the modem is setup as a bridge or it actually functions as a router?

 

[Murtaza12]

When connecting your laptop directly to the modem, do you have to setup your connection on the laptop, like a PPPoE, or it connects automatically via DHCP?
I guess what I really want to ask is if the modem is setup as a bridge or it actually functions as a router?

The IP Address has been assigned by the ISP to the modem as I have entered my username/password while configuring the modem so that could handle PPPoE.

When I connect to the modem through Ethernet cable, I get a private DHCP IP address from the modem (192.168.1.x).
So, yes it functions as a router.

My old modem from the ISP worked the same way, and I could trace route through that.

 

[Deepcuts]

The D-Link 2750U has a trace route and ping utility.
Does it work when doing a trace from the web config page?

 

[Murtaza12]

The D-Link 2750U has a trace route and ping utility.
Does it work when doing a trace from the web config page?

Yes, it did work.
When it was connected to my WDR3500 router, the ping/trace route utility of the router also worked fine.
Now, the trace route utility in the router also times out.

 

[Deepcuts]

That rules out any problems with your machines behind the router.
Unfortunately, either your ISP is blocking various ICMPs or a setting on the D-Link 2750U is preventing such ICMPs. (imho)

One more thing that comes to mind:
do a tracert -4 google.com just to be sure you are using IPV4 instead of IPV6.

 

[Murtaza12]

That rules out any problems with your machines behind the router.
Unfortunately, either your ISP is blocking various ICMPs or a setting on the D-Link 2750U is preventing such ICMPs. (imho)

One more thing that comes to mind:
do a tracert -4 google.com just to be sure you are using IPV4 instead of IPV6.

You may have confused my post.
When I WAS using the D-Link 2750U, the pings and trace routes were working fine.

Ever since I switched to a Wired TP Link TD-8840T, the pings still work, but trace routes time out.

 

[Deepcuts]

It seems i did
I was under the impression that the DLink is the new one.

 

[Murtaza12]

It seems i did
I was under the impression that the DLink is the new one.

No worries.

I ended up figuring it out. It was the Double NAT causing the issue since two private IP addresses were being issued:
192.168.1.x from modem to router (WAN)
192.168.0.x from router to wirelessly connected devices (LAN)

Hence causing a double NAT. It turns out that the D-Link modem had a feature to automatically disable double NAT or something like that, that is why everything worked fine on that.

What I did was:

Put modem into bridge mode.
Connect Ethernet cable from modem to blue (WAN) port on the WDR3500 router.
Instead of choosing Dynamic IP (WAN) option, I chose the PPPoE option. I entered the details that my ISP gave me.
IP Address was assigned to my router instead of my modem.
Double NAT has gone.

Rebooted both devices. Everything has synced up fine.
Andddddddd, double NAT is gone and trace routes and pings work.

 

[Deepcuts]

Glad you sort it out.
Just remember next time to explain your setup more clearly, because:
Weirdest part is, if I connect my laptop DIRECTLY to the modem through LAN cable, I still can't perform trace routes.
just tells me double NAT is not involved.

 

[Murtaza12]

Glad you sort it out.
Just remember next time to explain your setup more clearly, because:
Weirdest part is, if I connect my laptop DIRECTLY to the modem through LAN cable, I still can't perform trace routes.
just tells me double NAT is not involved.

Sorry about that.

Thanks for replying!