I've seen in other threads that the best and easiest way to reduce transmit power is by setting frequency mode to regulatory-domain and antenna gain to >0, but no matter what I try, from relatively low numbers like 5-20 to ridiculously high ones like 50000, I'm not seeing a consistent, appreciable difference. At first I thought maybe there's a minimum output level and I was just so close to the router that it couldn't drop off enough to be seen (even though that shouldn't matter and I should still see a difference), so I tested in another room, but still didn't see any difference. At a moderate level (don't remember, but between 5 and 50) I was getting about -70dBm, and dropping the gain to 0 resulted in it jumping to -40dBm, but then increasing it to 500 didn't change it. So either there's a maximum gain (which doesn't seem likely because going beyond that should just use the maximum, not zero) or it was just a random fluctuation. It seems like going from 0 to 20 and especially 50+ should make a huge difference. So what's missing? Is there another setting somewhere that could be preventing this from having an effect? This is with a Routerboard RB2011UiAS-2HnD-IN.

We can help you. Post the output of /interface wireless export hide-sensitive between forum code tags. The correct way to use antenna-gain is a combination of settings that need to be active or not.

Apply these rules in the terminal. Note the manual line at the end. You'll need to do that in the GUI. You have a lot of non-standard settings. Don't apply a gain over 20. Don't use wpa-psk (only wpa2 versions). Give this a try. Also, I would run 6.40.9 as the latest firmware (prior to the new bridge changes).

Thanks. I haven't done it yet, since I wanted to check regarding the firmware version, as mine shows the current version as 6.43.8, so wanted to see if I should upgrade to that one or if there's a reason you suggest 6.40.9. Also, is there a way for it to either automatically upgrade the firmware or at least alert me when there's an upgrade available (even if just popping up a message I'll see next time I log in to the router)?

Good point about WPA. I don't use it, but I didn't even think to actually disable it, so thanks for that reminder. It looks like that's what you're telling me to do for the last (manual/GUI) part, but then why only for the guest profile? And why in the "/interface wireless security-profiles" part are you having me change the key update time? And I'm assuming since no profile name is used it applies to all profiles?

Looking at the commands you posted, I don't see much difference from my current settings. Why are you changing it from b/g/n to just g/n? I realize b is ancient at this point, but does it hurt to keep it enabled? I also see you're disabling WPS, which is good, though I can't imagine that has anything to do with the goal here. Not saying it shouldn't be there, just wondering what part of those commands is actually changing things to make the Tx power reduction work.

Also, why not use gain >20?

Sorry for all the questions, just trying to understand it all as best I can. Figuring stuff out on this router has been quite the learning curve, and I still struggle with most of it.

And also try to avoid b-standard. This days you don't need, it's too old method.
btw The purpose of antenna gain is to decrease the power.

I know b is old, but unless it's a security issue, which I don't see why it would be, I don't really see the harm in leaving it for compatibility with older devices. That said, I highly doubt I would ever actually need it, and so I also don't see any harm in disabling it; I was just curious if there was a specific reason for disabling it other than just because it's dated.

And I know gain is for decreasing the power, the problem is raising the gain had no apparent effect.

If there's a reason you suggest 6.40.9?

It looks like that's what you're telling me to do for the last (manual/GUI) part, but then why only for the guest profile? And why in the "/interface wireless security-profiles" part are you having me change the key update time?

If you're going to run the long term versions, you should run the latest is all I meant by that. About the manual part, it was because the script I gave you would need to find your custom names for things and I did not take the time to do that correctly. When you have an interface, or name for something (an addition), you have to "find" it to get access to it and then applying a set against it.

Also, when I reply in this forum, others will read it over time. So, I provide the most correct settings I know, not merely answering your exact question.

I know b is old, but unless it's a security issue, which I don't see why it would be, I don't really see the harm in leaving it for compatibility with older devices. That said, I highly doubt I would ever actually need it, and so I also don't see any harm in disabling it; I was just curious if there was a specific reason for disabling it other than just because it's dated.

And I know gain is for decreasing the power, the problem is raising the gain had no apparent effect.

Hello,

As you support older standards, you may have a negative effect on overall performance as Wi-Fi will enter protected mode to accomodate everybody. I've decided to ban older standards and support 11n only. But you may decide otherwise based on your needs.

Cheers,

...
Also, when I reply in this forum, others will read it over time. So, I provide the most correct settings I know, not merely answering your exact question.

Great philosophy!! +1

I agree about posting so others will find it useful. The problem is, it didn't/doesn't look to me like any of the settings in the commands you posted would change anything, and after running them nothing did change (with respect to Tx power). The only differences in them vs my settings were the disabling of WPA (though only on the main SSID and not the guest one for some reason), WPS (though that's still enabled after running them), and b, and increasing the group-key-update time (again, only for the main SSID and not the guest one, and which I guess I'll change back since it doesn't seem to help and I don't know why it was set a 5 minutes or why it shouldn't be, but it must have been put there for a reason).

I did get "expected end of command (line 1 column 33)" after running the second set command, which I'm guessing is why WPS wasn't disabled for the guest SSID.

As for the firmware update (which I'd still like to know how to have it actually auto-upgrade, since it has an "Auto Upgrade" feature but I have no idea how to make use of it and everything referencing updating the firmware specifies the use of the packages tool instead), I swear the long term channel wasn't there before, so I upgraded to the latest stable (6.43., but then I couldn't restore my saved configs, since it was giving me a bad password error. So I switched to the latest long term release (6.42.11) which works for that. So not sure if that's a bug with the latest stable. And the reason I had to do that was because copy/pasting your commands in, I first tried using ctrl+v, which as it turns out (and I had to do some quick searching to figure this fun little tidbit out) enables an auto-complete mode, so it caused me to run the wrong commands (e.g. "/interface wireless" became "/interface traffic-eng erface wireless"). So whoever thought that was a good idea to make ctrl+v the shortcut for enabling that mode...

So anyways, still no luck getting this thing to lower its transmit power.

As you support older standards, you may have a negative effect on overall performance as Wi-Fi will enter protected mode to accomodate everybody.

But wouldn't it only do that if a device tried to connect with b? So if there are no older devices trying to connect, wouldn't it just run normally, and then if one connects, it would enter that mode, which would potentially cause decreased performance but at least it would work for that device?

So anyways, still no luck getting this thing to lower its transmit power.

I would suggest a firmware upgrade, followed by a clean system reset, then enter in settings I showed you for both main and guest. Note that as you increase gain, moving towards a max high of 20 (so start at 10), you will not notice a decrease in power immediately. Consumer devices do not show you real-time power levels.

As you support older standards, you may have a negative effect on overall performance as Wi-Fi will enter protected mode to accomodate everybody.

But wouldn't it only do that if a device tried to connect with b? So if there are no older devices trying to connect, wouldn't it just run normally, and then if one connects, it would enter that mode, which would potentially cause decreased performance but at least it would work for that device?

To be totally honest, not entirely sure how that would behave without 11b clients. But the AP would still send beacons announcing 11b support, so might it have an impact?

Beacons must be sent at the lowest speed the AP supports, with 802.11b this is 1mbps and a few APs nearby can take up a significant amount of channel bandwidth with just beacons. G/N only mitigates this significantly by mandating 6mbps minimum.

I wrote about this in more detail on my blog, https://r1ch.net/blog/wifi-beacon-pollution

Yes, the beacons and most control frames will be transmitted at the oldest and slowest supported method just in case there is an old device just about to associate. All transmissions will also start with a 802.11b header so the presumed old devices will know to wait. Note that transmitting data at the lowest rate can take 600 times longer. That will make a difference even if the header is short.

Another problem with 802.11b is that it takes 22MHz of bandwidth (instead of 20MHz of OFDM), which will pollute adjacent channels.

Thanks for the explanation. I read your blog post and it's certainly very interesting. I do have a few questions from it:

1) So even a protocol using one frequency (2.4/5GHz) and/or channel will affect the overall speed and therefore the throughput of another protocol on another frequency and/or channel?
2) Am I correct in understanding that while disabling g wouldn't make nearly as significant a difference as disabling b, it would still be quite dramatic? Or is it a diminishing returns type thing, and disabling it wouldn't be nearly as helpful?
3) Any idea how to increae the beacon interval in RouterOS? This was actually my first thought for dealing with this issue, since every 100ms just seems overkill and unneccessary.
4) Setting the minimum supported data rates above the rate of a protocol seems like it would just effectively disable that protocol, since devices wouldn't be able to make use of the beacon. Is that correct and, if so, what would be the point of doing that vs just disabling them?
5) A non-technical question, but I'm very curious: You're saying your local ISPs use customers' routers to allow other customers (but not everyone, so they're not actually open) to use each others' networks? This is both a very neat idea and a bit disturbing, since there would be no way of controlling what happens with your connection and no way of knowing who did what. Doesn't that create problems? Not to mention this seems like a potential security issue.

1) If the APs are on different channels then they won't be affected by each other, but keep in mind there is always risk of overlap (especially prevalent in 2.4 GHz with only 3 non-overlapping channels).

2) Correct, N also has a 6mbps minimum so it makes no difference.

3) Not possible yet, I posted it as a request somewhere as I also want to test the effects.

4) Not entirely sure here - depends a lot on the client.

5) Yes, they're implemented as a secondary SSID and isolated on a separate VLAN. There's some tagging interaction with the modem itself so it doesn't count towards your US / DS rates and the ISP can also identify whose traffic it is (it uses 802.1x for authentication IIRC) so there's less risk of abuse. Since it's still broadcasting on the same channel as your own SSID it will affect your wireless performance though, so I prefer disabling it.

I'll chime in again:
1) 2.4GHz and 5GHz bands are independent and won't affect each other. Same goes for non-overlapping channels in the same band. Note that 802.11b and 802.11g are only available on 2.4GHz.
2) 802.11b uses a completely different modulation (DSSS) so supporting such devices will require switching back and forth. 802.11g uses OFDM, which is also used for 802.11n and 802.11ac. They just use more advanced coding techniques and channel bonding to achieve greater speeds, but are backwards compatible with 802.11g.
3) Not supported ATM.
4) Remember that 802.11b supports 11Mbps. You would need to set the minimum to 12Mbps. I haven't tested but I expect there still would be an 802.11b header at the beginning of transmissions unless you specifically disable 802.11b.

Quick follow-up on #2: Just to clarify, there's no difference with g enabled vs disabled? It has to do with the minimum speed the protocol is capable of, not the speed of the slowest protocol? That is, I originally took it to mean that since b is slower than the others, the beacon had to be slowed down to match it, and since g is slower than n, it would have to be slowed down to match g (assuming b is disabled). But you're saying it's based off the minimum speed of the protocol, so since g and n both have the same minimum speed (6Mbps), that's what matters?

Anyways, as for the original issue, I've now disabled b, WPA, and WPS, but I still need to try resetting to default settings to see if that makes a difference with being able to adjust the transmit power. The problem with that is that I would then have to get everything set back up, which was a PITA the first time and, while I now have the settings to reference and a bit more experience with it, is not something I look forward to having to do again. But I suppose it'll be useful to at least see if the problem is fixed by resetting everything.

802.11n without 802.11g support in known as 'greenfield'. In mixed mode (the opposite of greenfield) all transmissions start with CTS-to-self and a non-HT preamble, which is a waste of bandwidth, if you don't have any pre-n clients. For the best results disable everything you are not going to need.