Rpi4 and ethernet, maximum cable length?

fjohnsen · June 14, 2021 at 5:43 PM

Hi,

I have been using kodi/libreelec with wifi for some time but as it sometimes lags I decided to try a wired connection instead. However when I try to change connection type the eth0 just "blink" idle and then disappears and then returns later one just to disappear again. Anyone that knows what this could be?

All cables between switch and rpi are cat6 (approx. 15m in total), it works just fine if I connect a 10m cat5e directly between the switch and the rpi. Is there a maximum lenght of ethernet cables that the rpi can handle? I plugged my laptop into the "port" in the wall and it works great, pings both internally and externally without any lost packages.

All support is appreciated.

**Klojum** · June 14, 2021 at 10:35 PM Official Post

100 Mbit & gigabit cable is designed to handle 100 metres.

**Da Flex** · June 14, 2021 at 10:59 PM Official Post

I'm using 12m Ethernet cable myself on an RPi - no problems. Make sure you have WiFi disabled at LE settings.

fjohnsen · June 15, 2021 at 9:55 AM

Wifi is disabled.

Can it be that the computer can handle the issues (incorrectly wired or faulty cables) but the rpi cant?

**Klojum** · June 15, 2021 at 11:53 AM Official Post

There is always the possibility of a cable having hairfractures, and that there are performance issues. Try a different cable, a different port in your switch/router, etc.

**Jocke.Sve** · June 15, 2021 at 12:44 PM

Just to mention;

There are few combinations of "CAT6" (and other CATx) cables.

For example "shielded" vs "unshielded", "CAT6" vs CAT6E" and all combinations of these.

Not all devices handle all types equally good.

**Klojum** · June 15, 2021 at 1:32 PM Official Post

I use shielded FTP cables, the price difference was negligible, and it won't hurt.

TonP · June 15, 2021 at 5:07 PM

What do you mean with "All cables between switch and rpi are cat6" ? Multiple connections ? Or cables extended ? If a Cat 5 cable works, but Cat 6 not, I suspect the Cat 6 cable. Are you sure there isn't a cross cable used instead of a straight one? How old is the switch? A connection between Pi and switch requires a straight cable, although most modern switches can adapt to a cross-cable.

**Da Flex** · June 16, 2021 at 3:17 PM Official Post

Quote from fjohnsen

Can it be that the computer can handle the issues (incorrectly wired or faulty cables) but the rpi cant?

No, Linux handles the Ethernet protocol perfectly. If your laptop can deal with the same Ethernet cable, check your router settings. Make the RPi a known and trusted device for the firewall (compare with your laptop settings).

marantz · June 16, 2021 at 3:28 PM

try le 10, I had so much trouble with cable and le9 with rpi4 so I used wifi instead.

now all is good

DoorkeyHDHR Prime · July 4, 2021 at 3:37 AM

Quote from fjohnsen

Hi,
I have been using kodi/libreelec with wifi for some time but as it sometimes lags I decided to try a wired connection instead. However when I try to change connection type the eth0 just "blink" idle and then disappears and then returns later one just to disappear again. Anyone that knows what this could be?
All cables between switch and rpi are cat6 (approx. 15m in total), it works just fine if I connect a 10m cat5e directly between the switch and the rpi. Is there a maximum lenght of ethernet cables that the rpi can handle? I plugged my laptop into the "port" in the wall and it works great, pings both internally and externally without any lost packages.
All support is appreciated.

For reference. I have this floating setup consisting of Pi 3b (27" computer screen) with LibreELEC 9.2.7 connecting over WiFi 40+ feet fromUbiquiti AP. Live TV works without any lag.