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I’m not a networking guru, but I know a lot of fellow crustaceans are. At home, my network performance between devices on local WiFi is pretty terrible. I was trying to backup ~20gb of data using syncthing and it was copying at 120kbps for two computers in the same room, but fast.com says I’m getting 20-30mbps down. I don’t know why the internal network performance is so bad.

At one point I tried tweaking the frequency and channel width to minimize interference but I’m not sure if/how much it helped.

The network is composed of two hotspots (an Apple airport and a MikroTik router both located next to the cable modem), as well as a WiFi extender.

What are some tools/techniques for optimizing wireless performance speed? What tools do you use for monitoring your home networks? Which resources are good practical guides for learning network tuning?

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    iperf3 is a handy tool for testing the link between two machines

    on one machine: iperf3 -s - this will be the “server” in this case

    on the other: iperf3 -c [hostname of the server]

    additionally, if you’re getting slow speeds for syncthing, it’s likely that the two machines are not connected directly. make sure the address for each device is the internal address and not routed through a gateway/relay

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      ooh, iperf3 is handy – I haven’t heard of that one. After running a test it looks like the link between the two machines is 20-30mb/s so it must be a misconfiguration in syncthing. Thanks for the suggestions!

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      The network is composed of two hotspots (an Apple airport and a MikroTik router both located next to the cable modem), as well as a WiFi extender.

      In the majority of situations having more than one active AP next to each other will do more harm than good. In an ideal world adjacent APs are always on different channels with a crossover signal strength of about -70 dBm.

      This analysis needs to happen independently for 2.4 GHz and 5 GHz bands. 2.4 GHz has much more penetration and range - so it’s common to have a number of dual band APs each on their own 5 GHz channel (which are much more plentiful), but only a select few have the 2.4 GHz radio enabled, since there are only 3-4 channels available and they interfere so easily.

      In summary try turning some stuff off; make sure everything you are using is on different 2.4 and 5 GHz channels; make sure you’re not using the “in-between” 2.4 GHz channels - e.g. in AU you would exclusively use 1, 6 and 11

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        In the majority of situations having more than one active AP next to each other will do more harm than good

        Yeah, I was wondering if this was part of the problem. I’m not totally clear on how WiFi works, but would bridging help them coordinate better?

        crossover signal strength of about -70 dBm

        What’s the crossover signal strength? I’m guessing it’s where the channels intersect (on one of these graphs).

        On the 2.4 GHz band one of the APs is on channel 11 (with the repeater on channel 11 as well) and the other is on channel 1. Only one AP has a 5 GHz band. I’ll try experimenting with the 5 GHz band a bit more since both computers are near the AP and don’t need the penetration of 2.4 GHz as much.

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          I’m not totally clear on how WiFi works, but would bridging help them coordinate better?

          It’s possible but this tends to be a manufacturer-specific feature of enterprise-grade APs. Those devices can automatically decrease their power levels or switch channels to avoid trampling on each other. They can also talk to each other to balance out their client loads.

          In your case none of this clever coordination will be going on. The best you can do is ensure that your three APs are not using any overlapping channels, on both radio bands - but if you get that right it will most likely be fine.

          What’s the crossover signal strength? I’m guessing it’s where the channels intersect

          Sorry I didn’t explain that well. Suppose you’re covering an area with WiFi that’s too large for a single AP so you decide to buy two of them. How close together should they be? If they’re too close it’s wasteful; if they’re too far apart there’s a risk of poor performance in the gap in the middle.

          When you’re standing close to one you might have a signal strength of -50 dBm. As you walk away from it you will have decent performance down to maybe -72 dBm, or less if your traffic is not too sensitive. So this is when you want to enter the coverage zone of the second AP and see signal strength start going up again, so that somebody walking around having a VoIP call doesn’t lose coverage during the handover.

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        Dunno if I’m stating the obvious here, but you haven’t specified:

        • if the issue is the same when the machines are hardwired
        • if both machines were connected to the same AP
        • if it’s all applications or just this one that you’re having problems with.

        Those would be the things I’d check first. It doesn’t sound like an optimisation problem it sounds like something is just not working properly or going severely wrong.

        You also didn’t state if you have a 2.4 or 5GHz network. It would be useful to get a 5GHz AP which as mentioned will have lower range but higher throughput. Congestion on 2.4GHz is much more likely.

        Perhaps if both your APs are next to each other, have their transmission power turned right up and you happened to connect two machines you want to transfer data between to different APs, it would mean that the traffic from each AP to each client might need an insane amount of retransmission and could cause something like this. I’m not expert enough in these things and no idea how to diagnose, sorry. Possibly something like this could still happen if both machines are connected to one AP but for some reason the other AP is broadcasting the traffic - perhaps some debugging potential there? Also what happens if you turn off your internet connection and just do this locally with clients that have no gateway to the internet?

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          if the issue is the same when the machines are hardwired

          I haven’t tried syncthing with a hardwire, but the performance for data transfer is much better when I connect them directly.

          if both machines were connected to the same AP

          They are – it’s a 2.4 GHz AP though, so there might be some extra congestion there…

          Possibly something like this could still happen if both machines are connected to one AP but for some reason the other AP is broadcasting the traffic - perhaps some debugging potential there?

          Hmmm… yeah a couple of other folks mentioned that multiple APs might be part of the problem. I’ll have to experiment with disabling one and seeing if the performance improves.

          I think the main problem is configuration in syncthing. I’m going to experiment with some options there before dropping to the network configuration itself.

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          A WiFi extender will generally trade range for performance.

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            How are you copying between computers? I’ve found SMB and AFS to be disappointing, but rsync or scp to be great.

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              A wireless site survey can help you select an open channel for your wifi network. Some wireless AP firmwares support this, or you could use something like this app on F-droid.

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                That’s a good idea – I don’t have an android phone, so I used wavemon and linssid instead, but they have views that are similar to WifiAnalyzer.

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                My current home network is easy because my home is small, my AP’s antennas are large, and my neighbors are just far enough out of range not to be an issue.

                When I was visiting my dad over New Year’s, though, interference was more of a problem. I didn’t have to get to anything sophisticated to run it down. I just grabbed kismet, and the (new-ish) UI made it easy to spot a better channel. I changed the channel on his AP and things were better as if by magic.

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                  Living in an old large house my flat is L-shaped. I’ve got an AVM router (FritzBox brand) and two WLAN repeaters of the same brand, but configured as WLAN bridge, NOT as repeater. Yes, I installed CAT6 cables from the router to the WLAN bridges. It is still one WLAN, only one point where I have to configure it (router webgui) and the configuration is shared from there to the WLAN bridges. Best WLAN I ever had. That said, I have CAT6 sockets in every room and if cables are possible, I use them. LAN is even better than WLAN. Why? No sporadic disturbances by the occasional weather station sensor or garage door opener or wireless remote control switch on the 2.4 GHz band.

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                    If the two PCs are connected to separate APs, syncthing might route the traffic via a node on the internet