Ethernet not working

[Mightyabhi]

Hi,
Im pretty sure its damaged for good but the PI seller told me its ok.

My ethernet port stopped working.I start the Raspberry Pi without the ethernet cable plugged in now i put in the cable the ethernet green/yellow light does not light up and now if i remove the ethernet cable both green/yellow ethernet lights light up.even if i plug ethernet cable back in again the lights stays up but still doesnt work. Eth0 shows up in terminal if i type ifconfig. Tries many ethernet cables none works in pi all works in pc. I put wifi dongle in it and it works.everthing works just not ethernet not even when i only put noobs on sd card and nothing else. Noobs shows no connection available.tge thing is i use my raspberry pi 2 for media center and hence have to copy paste files to and from it to mobile/pc and wifi gives half the speed that i used to get from ethernet. If u need any "SCREENSHOTS" of anything just let me know.i know it cant be fixed but maybe theres still hope.

[wh7qq]

Your post is confusing but the only thing that comes to mind is that you somehow contaminated or shorted the RJ-45 ethernet socket on the RPi. You can visually inspect it for contamination or loose wire and if you have access to electronic contact cleaner, use it to flush out the connector. Lacking contact cleaner, ethanol, available at hardware and paint stores is a substitute but make sure it is totally dry before you try to use the RPi (and for god's sake, don't drink the stuff as it is poisoned in most places). As your USB is still working, you could try to use a USB-ethernet adapter.

[Mightyabhi]

no there is no contamination or anything broken or loose i looked very closely. also before it went bad i just had checked it was working good came after 10 mins it wasnt working. 1 thing is that it was raining with thunderstorm and i use cable modem(the same black coaxiel cable which is used to run cable tv/setupbox maybe it shorted something. is there a way to fix it ? theres nothing odd looking burned or dirt or anything at all not on soldering or inside the ethernet port or anywhere else.

[wh7qq]

Damage from a static discharge or a short-circuit is definitely possible. What was the "black cable" connected to? Coaxial cable generally has two conductors: an outer shield and an inner core. If wired somehow to a mating connector, that could easily short an ethernet jack. Was it actually "coaxial" or was it a black ethernet cable...they are about the same size but the ethernet cable has 8 discrete wires in its jacket? Always be sure you are using the correct cable type with any electronic device. Even an ethernet cable can be miswired...easily. Best to buy cable with pre-installed connections and sold as Cat-5, Cat-5e or Cat-6 ethernet cable.

I would get an ethernet cable with terminations as sold with a router or internet cable modem and try to connect that between your RPi and your internet connection. If that does not work, take the RPi to a competent computer repair person and have them check it out.

[Mightyabhi]

black cable(yup actual coaxiel cable not ethernet/lan cable) is connected to my router(cable modem) and pi was connected to router using ethernet cable. but if there was some spike coming from black cable wouldnt it affect the router too ? coz the router is working fine.

[pcmanbob]

Hi.
Have you tried some basic tests.
Try plugging another computer in to the cable that was connected to you pi and if it connects to the router.
Try using another cable to connect the pi to your router and connect it to a different port on the router.
Let us know the results of these tests.

[drgeoff]

Damage from lightning strikes is unpredictable. On one occasion it knackered the ethernet port on my Set Top Box even though the ADSL modem/router it was connected to and everything else wired to the router survived.

So just because your router is OK is not a guarantee that a spike didn't clobber the RPi's ethernet port.