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I'm unable to get an ethernet connection with a raspberry Pi 2 over a cat7 cable of 40m. It works with my laptop, works over a short cable with same Pi. I used a same alimentation cable of 2.0A 5V

Cat7 cable

The reason I choosed cat7 cable was the price which was just 10% more and the perfs of this cable are better

Working

  • cable tested with a multimeter, every pins are working
  • Laptop connected to that same cable is working
  • Pi connected to LAN with short "normal" ethernet cable
  • I could get it work without problem twice and then disappeared!

Not working

  • two different raspberry pi hardware connected on this cable

Ping traces

20180220_1200

--- 192.168.0.17 ping statistics ---
6474 packets transmitted, 2843 received, 56% packet loss, time 6538201ms
rtt min/avg/max/mdev = 0.823/1.035/1.151/0.041 ms
Philippe Gachoud
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    at a guess, the pi's 8P8C modular connector socket doesn't physically play well with the GG45 plug on the cable - why use anything more expensive than Cat5e for a device barely capable of reaching 100Mbit? – Jaromanda X Feb 20 '18 at 01:57
  • Cause it does not consume any power and is nice to build projects! What do you suggest and based on what are you answering me that? Is there any documentation about ethernet interface of RPI? Thx @JaromandaX – Philippe Gachoud Feb 20 '18 at 16:46
  • Cause Pi does not consume any power and is nice to build projects! and, cable cat7 is not that more expensive, and reduces the losses on "big" distances. The ideal would be to do some POE with 40m which is normally doable... What do you suggest and based on what are you answering me that? Is there any documentation about ethernet interface of RPI? Thx @JaromandaX – Philippe Gachoud Feb 20 '18 at 17:24
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    My point was why use cat7 which isn't working when you can use cat6 which does work. I don't think you'll get any cat7 benefits even if it worked – Jaromanda X Feb 20 '18 at 20:23
  • "Category 7 cable are backward compatible with Class D/Category 5e and Class E/Category 6" source: https://en.wikipedia.org/wiki/ISO/IEC_11801#CAT7 . RPi can max. 100 Mbit/s, Cat5 should do the job. Maximum cable segment length is unexhausted. – Fabian Feb 20 '18 at 22:15
  • Beside the connectivity issue: Is your RPi operating in a normal way with the 40m power cable or does it show an "undervoltage warning"? Could you walk to RPi, connect a display and check? – Fabian Feb 20 '18 at 22:24
  • @Fabian its now working with contact spray (WD40 like). My Pi is connected with 220V->5V adapter which is a 2A adapter so thats not the point thx, but could be. – Philippe Gachoud Feb 21 '18 at 12:12

1 Answers1

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  1. Seems that an electronic contact spray into the raspberry pi ethernet connector solved my problem!

    --- molezonP2 ping statistics (1000 as packetsize) --- 415 packets transmitted, 415 received, 0% packet loss, time 419263ms

  2. Unfortunately for a time and after a physical disconect/reconnect it didn't work anymore again... got again 56% of packets loss

  3. After 3 days without touching it but connected got again a 0% packets loss

Philippe Gachoud
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  • And this was the solution for both not working raspi? And the short cable does not need this? Curious ... I have similar problems with unstable ethernet connections. Do you use avahi for mdns and/or upnp for multicast media in your network? – Ingo Feb 25 '18 at 13:31
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    @Ingo Yes, but seems that I still have issues, didn't find why it works sometimes 100%, I disconnect it and reconnect it later and doesn't work @ all, after some time I get 50-60% packets loss, I'll let a trace here when I find the solution but am still fighting with it. I actually use nmap to discover it, and my dhcp server which is my ISP router. – Philippe Gachoud Feb 27 '18 at 00:58
  • I'm happy finding one who confirms this general weakness of the ethernet device. I'm fighting with ethernet device interrupts connection since weeks. – Ingo Feb 27 '18 at 11:11
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    Can you please edit your answer and explain that the problem persists? – Ingo Feb 27 '18 at 14:56