MR2200ac Why does the MR2200 handle weak backhaul signal so poorly?

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MR2200ac Why does the MR2200 handle weak backhaul signal so poorly?

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  1. RT2600ac
  2. MR2200ac
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I would like to confirm if my expectations are out of whack here. I have a mesh network setup with:

RT2600 (A) <- 5GHZ -> MR2200 (B) <- 5GHZ -> MR2200 (C)

The signal between A and B is about 2 bars in the SRM web GUI. The signal between the two MR2200 devices is typically listed as a single bar of signal and "unstable connection to wifi points" in the SRM. In the logs, I see it typically disconnects and reconnects a few times a day which takes a few mins of downtime.

Now, these routers are out in the countryside... very little neighboring electronic noise. Router A and B are about 8m apart and there are 2 interior walls between them. Router B is on a windowsill facing Router C which is in the living room of a guest house next to sliding glass doors. I would say there are about 15m between the two devices and they basically have line of sight.

The things that kind of irk me about this are:

- I would not expect 1 bar of signal between 2 routers that basically have 15m and line of sight and 2 windows between them.
- If the signal is too weak for 5GHZ, I would expect it to be able to decide to switch to 2.4GHZ without the backhaul going down.

Overall, the signal from these routers seems quite weak, and the software seems to not know how to deal with weak signals very gracefully. Has anyone else experienced this kind of situation or have any suggestions for me?
 
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Unfortunately i do not have a solution but i have similar setup and issues.. the transition from the router to the MR220 device seems also to be laggy. my phone will work for some minutes and then I have to disable/enable the wifi to have a stable connection... I will keep an eye on this thread..
 
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  1. RT2600ac
  2. MR2200ac
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  1. macOS
Mobile operating system
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I think I'm going to try to measure the attenuation between the window open and closed and see if I can nail down the falloff in 5GHz caused by the building materials. I can't seem find find any specs about what kind of 5GHZ backhaul signal strength I can expect from an unobstructed MR2200AC unit at a particular distance... but I suspect the antennas inside are just too weak.

...and none of that addresses the fact that the thing behaves pretty badly when the signal is weak and doesn't just flip to 2.4Ghz and stick with it but instead goes on/offline constantly.
 
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fredbert

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I'm not sure how the mesh is working between routers but I remember it used to be said that using repeaters, like in WDS, would halve the bandwidth for each repeater. But why would that affect signal strength? It did occur to me that there may be metallic insulation coatings that are put on glazing units, but I only thought that because it would explain why the signal drops when in all expectations it shouldn't.


I see you're using a Mac, so if you have a MacBook (big 'if') then I'd really recommend using WiFi Explorer, or similar WiFi signal tester (look in the Mac App Store for WiFi Explorer and there's a lot of other options). Using an app like this while walking about will show you where the signals drops.

For example, for a ticketed event, we needed to get a strong enough WiFi signal across a cricket pitch from the club house. This was for an event where the pitch wasn't being used and the mobile signal was getting swamped. Using the scanner we found the easiest solution was to relay the main SSID rather than adding a new wired router outside: we considered running 200+ m of cables. Using a TP-Link travel router in relay mode, attached to a hefty battery pack and in a plastic lunchbox, held up high using a bicycle maintenance stand, we placed it as near to the wicket as possible (playing centre of the pitch), without annoying the groundsman, and were able to get a reliable 20Mbps signal. And I had this kit spare :)
 
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I'm not sure how the mesh is working between routers but I remember it used to be said that using repeaters, like in WDS, would halve the bandwidth for each repeater.
This is true for repeaters but not mesh routers. They have dedicated backhaul radios which are in a ‘hidden’ SSID separate from the radios being used to talk to clients.

I see you're using a Mac, so if you have a MacBook (big 'if') then I'd really recommend using WiFi Explorer, or similar WiFi signal tester (look in the Mac App Store for WiFi Explorer and there's a lot of other options). Using an app like this while walking about will show you where the signals drops.
Yes, this is exactly what I am doing to measure it. Without an app like WiFi Explorer you only have the SRM and it doesn’t really display the backhaul signal strength in very much detail at all.
 
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fredbert

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This is true for repeaters but not mesh routers. They have dedicated backhaul radios which are in a ‘hidden’ SSID separate from the radios being used to talk to clients.
Indeed. I see the hidden SSID in WiFi Explorer and, I can't see as I use wired back haul, I would guess the MR2200ac APs use 5GHz-1 (the single one one the RT2600ac) and then they use 5GHz-2 for device connections. Or do they alternate 5GHz-1 and -2 until an AP has to connect to the RT2600ac? For the single 2.4GHz band they must have to share with the visible SSID.
 
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There is always bandwidth losses when using a radio back-haul vs a wired one. You lose the duplex bandwidth of wired back hauling with the move to simplex radios, management frames increase, beacon frames increase, the ack rate of WiFi UDP frames doubles, pause frames increase, the level of retransmissions increases tends to double, with double the risk of interference from external factors, a signal and power envelope that has to manage self & mutual interference and all this from a smaller bandwidth bucket caused by the first radio hop.

I could go on to add mismatched antenna size & gain, plus the reversal of asymmetrical traffic at the mesh point but you get the idea that mesh is difficult, especially in real-world conditions where air-time is a critical factor.
 
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