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I'd like to extend internet service to an outbuilding that is 600+ft from my house. The distance is heavily wooded, so I think a wireless solution is a non-starter (but correct me if I'm wrong).

This ethernet expander looks like it could do it. The description claims it can support 100 Mbps over 1000ft, using VDSL. (I don't need the full 100Mbps, but would like to have at least 20Mbps or so).

They also claim it works with "copper phone wire". It turns out that I have a lead on a long-enough spool of coax, for cheap or free. I'm wondering how it would work with this device ? I realize I need to wire it to RJ45 connectors at each end. I would probably just lay the line along the forest floor (the way I do with low-voltage wiring for landscape lights) where it just gets naturally buried by leaves and such.

  • This seems to be more of a networking question, which may be better suited for the serverfault.com group – binarymax Mar 6 '18 at 15:20
  • I wasn't sure where to put it. So do I just delete the question here and repost it there ? – RustyShackleford Mar 6 '18 at 15:24
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    You might be using the wrong term, but "coax" is for RF signals like cable TV and is not compatible with the device you linked. MOCA adapters are used for ethernet over coax. – JPhi1618 Mar 6 '18 at 15:34
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    If the device will work over ordinary phone wire, which is just two copper conductors (usually 4, but only 2 are used), I don't really understand how coax could be worse. – RustyShackleford Mar 6 '18 at 16:08
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    @RustyShackleford Phone wire uses twisted pairs to ensure that the current is always balanced in the two wires. Coax is intentionally unbalanced, which could cause problems by itself. And phone wire actually does have an impedance, so you'll still have a mismatch. You're welcome to try it, but I'd be surprised if it works very well. – mrog Mar 6 '18 at 18:38
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You can, but it's a VERY poor solution. You've crossed into my professional sphere of operations.

Also, if using coax, get extenders that are intended to work over coax - twisted pair and coax are quite different. Both types of converters are made.

Even if the mere thought terrifies the heck out of you, fiber is the sensible solution to this problem. It should not be terrifying. I have done long connections (using various, often expensive, adapters and line extenders) on coax, twisted pair and fiber. All three technologies will do the distance with appropriate converters at the ends (speed won't be great on either of the copper solutions though - perhaps 30-40 Mbit in my experience at those distances. Less with crappier electronics.) Only one of them will work consistently in the real world where lighting happens - that one will also work at gigabit (1000Mbit) or faster speeds.

Been there, done that, have the burnt hardware to show for it. Fiber has permitted calm to prevail when thunderstorms visit.

In most cases, rather than getting a "fiber media converter" you will be better served and out less money for a gigabit (or 10 gigbit if you are really need-for-speedy) switch with SFP (SFP+ for 10 gig) slot or slots. Two low-cost switches, SFPs and 200 meters of pre-terminated fiber will probably cost less than a pair of copper line extenders - two factors - one a simple issue of scale - there's a limited market for copper line extenders, while there's a vast market for Ethernet switches, SFPs and fiber - the second is that there's some specialized electronic voodoo going on in a good line extender, while the fiber system is stock-simple. Getting paid for your voodoo in a small market makes for a high price tag.

As for wireless, how much chainsawing are you willing to do? You don't need a huge hole to get 5 GHz through at 600 feet - 5 feet wide and high will do. Technically, that big at the mid-point and less going to each end will do (google Fresnel zone if interested in the details.) Shooting through trees is iffy, but shooting through a hole in the trees is not. If TRYING to shoot through trees without clearing a hole, your odds improve at 900 MHz, but the equipment is less common and more expensive than 5 GHz stuff for point to point.

The cable should be bonded to the electrical ground at the service entrance of each building. This should help with, but does not consistently prevent, in my experience, damage from lighting-induced surges. If you get a direct strike, nothing really survives that, but that is not common. Fiber has the advantage of being completely electrically isolated, as well as being much faster connection. It's the best network surge protection money can buy...

As for laying the cable (of whatever type) on the forest floor, good luck with that. Rodents with teeth... I'd strongly suggest looking for a possible 5 foot hole through the trees, and chainsaw half a dozen if needed to make it, rather than flaking cable on the ground. Try a bright light at one end and looking from the other end in the dark.

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    Another option if you want to try wireless without cutting the trees is to place a passive repeater on a hill/building/tower/whatever on your property. It would have to be in a spot that has a clear line of sight to both your house and the outbuilding. A passive repeater is basically just two directional antennas wired together, one antenna would be pointed at your house, and the other at the outbuilding. The house and outbuilding would also need their own directional antennas pointed at the repeater. And, of course, all the antennas would need to match the frequency in use. – mrog Mar 7 '18 at 20:40
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Do the house and outbuilding both get power from the same transformer? If so, you could try a power line ethernet adapter. I've heard of them working up to about 1000 feet. So depending on how your power lines are routed, it might work well enough. For best results, you should make sure the adapters on each end are connected to the same phase of power. I wouldn't expect really high data speeds at that distance, but it would be a cheap and easy thing to try, anyway.

  • They do not. I think transformer isn't supposed to be more than 250ft or so from house, so ... – RustyShackleford Mar 8 '18 at 0:02
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If you can obtain the Coax cable, some "100-Base-T Ethernet over Coax (EoC) Adapters" will do the trick.

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    Interesting that a passive device can get a usable signal through 850ft of coax. Cool if it works, but I'd want to have a backup plan as well. – JPhi1618 Mar 6 '18 at 15:38
  • That's an interesting device. The maximum distance will depend on the type of coax used. From the manufacturer's website: Transmission distance up to 800ft (RG6)/600ft (RG59). – mrog Mar 6 '18 at 16:02
  • Yeah, they say "existing in-home coax". Makes me suspicious. "Up to 850ft" sounds like the figures that cordless telephone mfg'ers quote, actually meaning "there's no way in hell you are going to get this". – RustyShackleford Mar 6 '18 at 16:06
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    Given the distance to the outbuilding, you're going to need all the power you can get into the coax. That means you can't have a long ethernet cable connected to the coax adapter. Depending on how your network is set up, you might need to add a hub or switch right before the adapter to boost the signal. – mrog Mar 6 '18 at 16:08
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No, ethernet range is limited to 100m = 300ft so even with a cable your network won't work due to ethernet specifications. Only way to make it work is to reduce each trunk to less than 100m putting a store-and-forward device in the middle (switch ->OK, hub -> KO). You can opt for a 10base5 network, but that kind of hardware is decade-old, very slow (10 Megabits), and incompatible with modern systems. Ethernet solution can be 100 baseBX (fibre-optic)

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    The 100 meter limit is based on the spec that also calls for twisted pair wire. The attenuation of coax is different, so the range will also be different (either more or less, depending on the type of coax). Of course this assumes that the right adapters are used. If you just stick an RJ-45 connector on a coax cable, it's not going work well at all. – mrog Mar 7 '18 at 20:30
  • Attenuation doesn't matter, what matters is the RTT over the cable. RTT shouldn't be longer than the time required to transmit 64 bytes that is the minimum frame lenght allowed by the standars. – DDS Mar 7 '18 at 20:52
  • I don't think the time it takes to transmit is the problem - whether you're transmitting an electrical signal through copper or a light signal through fiber, both signals will travel near the speed of light. The copper does have other limiting factors to consider though. – CactusCake Mar 7 '18 at 21:11
  • @DDS Attenuation and RTT both matter. It doesn't matter how fast a signal arrives if it's too weak to be received. And, unless you're talking about extreme distances, almost none of the RTT time is caused by latency in the cable. Cat 5e, for example, has a velocity factory of about 0.74, so it takes a whopping 4.5 x 10^-7 seconds for a bit to travel 100 meters in it. Coax cable tends to be slightly slower with a velocity factor in the 0.6 - 0.7 range. But it's not going to affect your ping time significantly, even over a few thousand meters. – mrog Mar 7 '18 at 21:11
  • RTT is the king: CSMA-CD cannot detect collisions if happen 'farther' than 64Bytes, so network won't work, even if signals are clear. – DDS Mar 7 '18 at 21:15

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