I needed to connect two buildings and was having machines in to dig a 4’ (1.2m) deep trench between them for a water line so I went to Amazon and bought a 250’ (76m) pre-terminated copper Cat6 cable. As I was going to be burying it I wanted to be sure it worked, so I used it as a “fly lead” for my laptop for a week or two first and it worked fine. I know it initially connected at 1Gbps, but (stupidly) I can’t be 100% certain it stayed at full speed the whole time.

Now that it’s buried I’m only getting 100Mbit/s. It does sometimes connect at 1Gbit/s, but it later falls back to 100Mbit/s. I have an old Cisco SG300-10P on one end and a Ubiquiti Edge Router X on the other. I disabled 802.3 Energy Efficient Ethernet (EEE) on the Cisco and, as expected, it made no difference. The Cisco has built in cable test capability and it says I have an 84m open cable on all pairs - even when connected to the ER/X and working. Is there some sort of loopback/test termination I can make for the other end to get a better (more meaningful) result? I’ve tried searching, but failed.

The plug at one end did get pushed through some silicone caulk as it was being shoved through a hole in a wall. I cleaned it off with alcohol and it looks clean, but I’m considering cutting the plug off and replacing it with a socket as my next debugging step as it would be more convenient anyway.

I live about an hour from the nearest large town so there’s no way I’m getting someone here with a proper tester at a reasonable price. If I can’t figure it out myself I’ll revert to the pair of airMax GigaBeam radios that have given me a solid 800Mbit/s for the last 3 years with only visual alignment!

Edit: this is the cable https://a.co/d/i6mYLy1

  • hereiamagain@sh.itjust.worksEnglish
    2·
    6 days ago

    Did you ever figure this out? I’m curious. Nobody mentioned the caulk, yes you cleaned it, but if it was silicone then it likely cures with acetic acid, which can corrode the conductors on both sides of the plug.

    • Great Blue Heron@lemmy.caOPEnglish
      1·
      6 days ago

      I think I’ve figured it out, but have not fixed it.

      I’m fairly sure it’s a ground loop type issue. It comes and goes. It ran at 1Gbps for a few weeks at one point and I thought it was resolved, but it’s now back to 100Mbps.

      I have a few options - I have a pair of Ubiquiti airmax gigabeams that I can put back into service, I can dig a shallow trench and bury some fibre (it only recently occurred to me that fibre is not electricity so doesn’t need to be down 2’) or I can dig a shallow trench and bond the ground between the two buildings.

      The gigabeams are obviously the easiest, the fibre is the best (and what I should have done in the first place) and bonding the grounds would only really be out of curiosity to see if it actually works.

      And with your advice I have another option - double check the contacts for cleanliness and possible corrosion.

      • hereiamagain@sh.itjust.worksEnglish
        1·
        6 days ago

        Thanks for the update!

        I’m not a professional, just some ideas here:

        Yes cat6 is copper, but it’s low voltage, so according to a quick Google, you can put it 6 inches under and be ok, depending on what’s on the ground above it.

        Fiber sounds good, but more delicate if anything is driving over it, might want it deeper anyway. For what it’s worth they just installed it at my house and only trenched it 2 or 3 inches, so 🤷‍♂️

        You mention bonding the buildings together, and that might work, but there might be some code violations there, definitely look into it. IIRC if bonding two buildings, you need to, at a minimum, drive a ground rod 8ft down every so many feet. On every 5 or 10 maybe? Don’t quote me, definitely look it up.

        But you might not need to do that anyway, did you try grounding just one side, or the other side? Just making sure the shielding on one side or the other is bonded well to the ground in that one building, and not the other. RF can do some weird stuff. And a wire that long is basically a big antenna, and if not grounded, can be inducing all kinds of voltages and noise where it shouldn’t be.

        The RF link did work great, but it’s hard to beat a solid chunk of wire. That REALLY should be working for you, sorry to hear it’s not.

        Anyway sorry to butt in with my opinions, please do keep us posted! I’m quite curious now haha

      • HubertManne@piefed.socialEnglish
        2·
        6 days ago

        sorta curious but why did you opt to bury the cable rather than run a pipe that you could run cable through?

        • hereiamagain@sh.itjust.worksEnglish
          1·
          6 days ago

          Not op, but sometimes you just do the quick easy thing with the assumption that it should be fine for a good long while. And then it isn’t 🤦‍♂️

        • Great Blue Heron@lemmy.caOPEnglish
          2·
          6 days ago

          I’d had good luck running similar length copper outside, between buildings, in the past. I had regular blue indoor cat5 just under the surface, tacked to the bottom of fences etc for 7 years and never had a problem with it. Dropping a roll of pre terminated cable built for direct burial in the trench seemed like a no brainer.

          With the benefit of hindsight - having that 4’ deep trench open was a once in a lifetime opportunity that I should have better taken advantage of.