Super weird Internet speeds after changing Lan cable from modem to router

cracmeister · February 11, 2020

Hey everyone!

I am experiencing super weird problems at my home network.

My setup is:

Cable modem from ISP, 1 m cat6 lan cable to router (Linksys Velop)

I test speeds in the Linksys app, which is supposed to measure the speed it receives from the modem.

I also test just with my android phone using various speed test(I thought it could be a speedtest.net error)

And I test using my pc which is directly connected via Lan to the router.

I used to receive 300/30, exactly what I pay for.

But yesterday I switched some Lan cables from the switch I normally have connected and I think I touched the cable from modem to router.

Suddenly the speeds sucked ass. 0.6/3 or 12/5 just weird stuff, everytime I speed test different results. Of course I tried the usual troubleshooting steps, disconnecting modem and router and connected devices from power for extended periods of time, called ISP, they said everything is fine on their end. Reset whole Velop system. Changed Lan cables...

My thoughts now are that either the modem is bad, which I want to try using a different router so I can proof this.

Or my weird theory:

I had this issue before, that when I touched the Lan cable between router and modem a little harder, so that it would move a little, the connection went bad. I then just restarted everything and swapped Lan cable, or just tied to move it differently. After 15 minutes or so I usually got it to work again.

But now I can't get it back. So is there a possibility that the Lan port on the modem went bad? I am pretty sure it's not on the Velop side, because I also swapped out the Velop APs to make another node the main node.

I couldn't find any information on bad Lan ports on modems. Please help..

Norwegiantweaker · February 11, 2020

29 minutes ago, cracmeister said:

Hey everyone!

I am experiencing super weird problems at my home network.

My setup is:

Cable modem from ISP, 1 m cat6 lan cable to router (Linksys Velop)

I test speeds in the Linksys app, which is supposed to measure the speed it receives from the modem.

I also test just with my android phone using various speed test(I thought it could be a speedtest.net error)

And I test using my pc which is directly connected via Lan to the router.

I used to receive 300/30, exactly what I pay for.

But yesterday I switched some Lan cables from the switch I normally have connected and I think I touched the cable from modem to router.

Suddenly the speeds sucked ass. 0.6/3 or 12/5 just weird stuff, everytime I speed test different results. Of course I tried the usual troubleshooting steps, disconnecting modem and router and connected devices from power for extended periods of time, called ISP, they said everything is fine on their end. Reset whole Velop system. Changed Lan cables...

My thoughts now are that either the modem is bad, which I want to try using a different router so I can proof this.

Or my weird theory:

I had this issue before, that when I touched the Lan cable between router and modem a little harder, so that it would move a little, the connection went bad. I then just restarted everything and swapped Lan cable, or just tied to move it differently. After 15 minutes or so I usually got it to work again.

But now I can't get it back. So is there a possibility that the Lan port on the modem went bad? I am pretty sure it's not on the Velop side, because I also swapped out the Velop APs to make another node the main node.

I couldn't find any information on bad Lan ports on modems. Please help..

did you try new cable.. you say that when you press/touch the cable from modem to switch the signal goes bad. wouldnt it then only be logical that.... the cable is broken ... ?

cracmeister · February 11, 2020

14 minutes ago, Norwegiantweaker said:

did you try new cable.. you say that when you press/touch the cable from modem to switch the signal goes bad. wouldnt it then only be logical that.... the cable is broken ... ?

I swapped cables multiple times. switched between cat5e and cat6 cat6a even cat7, which doesn't make a lot of sense, but I tried everything.

Right now I did swap cables again, and briefly I had my 300/30, then I tried to bend the cable another way and speed was gone. so it is definetly something with the lan port on the modem. just weird, looks perfectly fine to my eyes...

And of course I can't replicate the perfect angle of the cable again, and on the long term I don't want to rely on the right angle of a lan cable just to make my internet work.

But how can that be? Isn't it like all the contacts make contact and the connection works. How can it be that a different angle gives me full speed?

it's a cisco cable modem

Alex Atkin UK · February 11, 2020

5 hours ago, cracmeister said:

I swapped cables multiple times. switched between cat5e and cat6 cat6a even cat7, which doesn't make a lot of sense, but I tried everything.

Right now I did swap cables again, and briefly I had my 300/30, then I tried to bend the cable another way and speed was gone. so it is definetly something with the lan port on the modem. just weird, looks perfectly fine to my eyes...

And of course I can't replicate the perfect angle of the cable again, and on the long term I don't want to rely on the right angle of a lan cable just to make my internet work.

But how can that be? Isn't it like all the contacts make contact and the connection works. How can it be that a different angle gives me full speed?

it's a cisco cable modem

Its actually not so weird, if the solder joints have gone bad between the socket and the PCB then bending the cable would cause them to make better contact.