New router, lower signal. Help to strengthen it?

Installing and Using OpenWrt Network and Wireless Configuration
1

Hello everyone. My first message here, hopefully someone will help.

Small caveat before I start: I live in the middle of nowhere, and the nearest neighbour who may have some wifi signal going on is about 3-400 meters away from me (and 50-60 meters higher), so no problems whatsoever for what concerns risks of interference with other people wifi.

Now to the problem. Until today, I had a TP-Link TD-W8970 as my main router. This router has three detachable antennas, and to one of the connectors was attached an outdoor antenna similar to this one: https://www.tp-link.com/en/home-networking/antenna/tl-ant2415d/ (might be the previous model, but it looks the same). The router had LEDE installed, flavour from here: http://ofmodemsandmen.com/ (my internet connection is through a 4G internet key, and this particular firmware is great for handling them, I had the 2017 firmware installed, based on LEDE 17.01.4). With such a configuration I was able to provide wifi signal all over the outdoor area of my house, see image below (up to ~ the green line, the outdoor antenna is the red dot):

area2
area2594×1252 81.3 KB

Because the router is very old, plus I'm at home only once-twice a year, plus I wanted to do more things that the limited cpu/ram/rom combination of the router would allow me to, I replaced it today with a Linksys WRT3200ACM, to which I installed the same firmware as above (but the 2020 build, based on OpenWrt 18.06.7). The WRT3200ACM has 4 detachable antennas, so once again to one connector (the one on the left to be precise) I attached the outdoor antenna. In the new router, the 2.4 GHz radio is set to channel 11, 40 MHz width, and to the maximum power output the LuCI interface will allow me to select (20 dBm, 100 mW).

My problem is that with the new router the area reached by the outdoor antenna is reduced, more or less up to the blue line in the figure. Circled in yellow is an outdoor area where I need to have some connection, even if not a fast one, which I'm not having right now. My question is, then: is there a way to tell OpenWrt to pump a bit more power out of the 2.4 GHz radio, so that I can reach that yellow area? As I said, no risk of interferences/bothering the neighbours.

2

Modern wifi standards (since 802.11n, but much more pronounced with 802.11ac and 802.11ax) rely heavily on (Mu-)MIMO, multiple spatial stream transmitted over different antennas, fine tuned to the specifics of the stock stock (omni-directional-) antennas. Replacing one of them with a directional antenna breaks this system, resulting in lots of transmission failures - it's not a good idea.

3

the outdoor antenna is also omni-directional, although I agree that the fact that it only handles 2.4 GHz signal (802.11n) and that it's not placed together with the other three antennas doesn't help much. However, the old router was also 802.11n and had (if I remember correctly) some form of MIMO, and everything has worked well until now. While I agree with you that the setup is not ideal, it still works for what I need it to do. My question then remains: is there a way to allow the new router to reach the same coverage area as the old one?

4

As per usual @slh is correct. I think the easiest thing to do would be to daisy chain the old router off of the new one and connect the outdoor antenna to the old router as you had previously.

Daisy chaining it in router mode will result in double nat - but if you just need internet connectivity that should be good enough. If you need the AP to be on the same subnet as the 3200 then you would have to configure it as a dumb AP.

I don't think its worth spending the ~$100 on 4 new antennas and cabling in order to externally mount them outdoors seeing as the old way works and doesn't cost anything. The WRT3200ACM is known to have bad 2.4Ghz coverage. Plus mounting all the antennas outdoors may introduce coverage problems indoors. Then what?

....but if you really wanted to you could buy some dual frequency 12db antennas for it (I think that's what it uses) and place the router in a window with something close to a line of sight to the area in question - that would be under $40USD. 12db dual frequency antennas commonly available from all the major online retailers. That would be up to you to order the correct ones and test - but that's not really guaranteed to work either. Some of the cheaper antennas overstate their gain values so it could all just be a big waste of time and money.

You would have to plug some numbers into an antenna gain calculator to see if you are in compliance with local regulations. If it exceeds allowable limits turn down the gain. I punched in the numbers and got a gain value of ~30db @ 2.4Ghz which should be okay but that would be up to you to test and verify. None of this might work and could be a waste of money and cause a lot of frustration, whereas the old way worked. That's up to you to decide.

HTH

5

Ok, I see. Thanks for all the answers!

6

You can get 7db of more gain if you change the channel for 5Ghz to 149 or higher.

Frequencies:
                        * 5180 MHz [36] (23.0 dBm)
                        * 5200 MHz [40] (23.0 dBm)
                        * 5220 MHz [44] (23.0 dBm)
                        * 5240 MHz [48] (23.0 dBm)
                        * 5260 MHz [52] (23.0 dBm) (radar detection)
                        * 5280 MHz [56] (23.0 dBm) (radar detection)
                        * 5300 MHz [60] (23.0 dBm) (radar detection)
                        * 5320 MHz [64] (23.0 dBm) (radar detection)
                        * 5500 MHz [100] (23.0 dBm) (radar detection)
                        * 5520 MHz [104] (23.0 dBm) (radar detection)
                        * 5540 MHz [108] (23.0 dBm) (radar detection)
                        * 5560 MHz [112] (23.0 dBm) (radar detection)
                        * 5580 MHz [116] (23.0 dBm) (radar detection)
                        * 5600 MHz [120] (23.0 dBm) (radar detection)
                        * 5620 MHz [124] (23.0 dBm) (radar detection)
                        * 5640 MHz [128] (23.0 dBm) (radar detection)
                        * 5660 MHz [132] (23.0 dBm) (radar detection)
                        * 5680 MHz [136] (23.0 dBm) (radar detection)
                        * 5700 MHz [140] (23.0 dBm) (radar detection)
                        * 5720 MHz [144] (23.0 dBm) (radar detection)
                        * 5745 MHz [149] (30.0 dBm)
                        * 5765 MHz [153] (30.0 dBm)
                        * 5785 MHz [157] (30.0 dBm)
                        * 5805 MHz [161] (30.0 dBm)

But 2.4Ghz is already at 30db fixed. May be able to change country code for higher strength.

Frequencies:
                        * 2412 MHz [1] (30.0 dBm)
                        * 2417 MHz [2] (30.0 dBm)
                        * 2422 MHz [3] (30.0 dBm)
                        * 2427 MHz [4] (30.0 dBm)
                        * 2432 MHz [5] (30.0 dBm)
                        * 2437 MHz [6] (30.0 dBm)
                        * 2442 MHz [7] (30.0 dBm)
                        * 2447 MHz [8] (30.0 dBm)
                        * 2452 MHz [9] (30.0 dBm)
                        * 2457 MHz [10] (30.0 dBm)
                        * 2462 MHz [11] (30.0 dBm)
                        * 2467 MHz [12] (disabled)
                        * 2472 MHz [13] (disabled)
                        * 2484 MHz [14] (disabled)
7

the linksys WRT3200 and 32x do have a specific issue, when the country code is manually set incorrectly and/or when radio 3 country code is mismatching the country code of the other radios. This results in a noticably reduced TX power, which does not show in LuCi, as its a wifi hardware binary firmware behavior.

Outline of a proper workaround was: You have to set the default (I think is was 99) country code on radio 0/1, but via command line and the country specific code on the third radio. An alternative fix was to completely uninstall the third radio to avoid issues.

There were precise forum discussions about this, I unfortunately cant seem to find it right now.

Since you specifically mention low radio power issues, I would first try the stock firmware with stock antennas, such that you have a reference TX power experience.

then as next test, I would keep the stock antennas, try stock OpenWRT 18 or 19 with stock antennas without modified country code. An then try customizing the country code and/or disable third radio as suggested.

Then as last test use the custom antennas.

8

On both the venom and rango the power table as embedded by the OEM for distribution locale dictates the device capabilities. You cannot override either the CC or the TX power, what you get is the maximum TX power for the channel selected for the country of the device; i.e. if you have an EU unit it is FR and TX power for channel choice. You should not set either as you cannot override, and the CC may cause problems if in disagreement with the third radio; or set them as per unit sticker.

There is a patch available to allow one to set the CC, but it does nothing to allow overriding the TX power.

9

@Pico and @anomeome thank you for your replies. Yesterday night I started reading all the topics related to my new router and I read the problems with the country code and so on. Today I factory reset everything, uninstalled the kernel module for radio2 to avoid problems and I've done a couple more tweaks to the wireless configuration as suggested in other threads in this forum and now I've managed to extend the range of the outdoor antenna and reach the area that I needed to reach. Thanks again to everyone who helped! It's really a pity that I cannot change the country to something that allows a little more power (as I said, I'm in the middle of nowhere, so no risk of creating interferences), but I'll live with that.

1 Like
10

You don't have to change countries. You can just try different routers. All of my routers only do 199-316mW on 2.4Ghz even though for example you are allowed 1000mW in my country because they came from other countries where that was the max. You could add an amplifier or a parabolic antenna within EIRP limits? If your neighbors are out of range then it wouldn't matter as much? Time to make a MESH network?