Archer C7 V2 / Archer C5 V1.2 - WiFi 5 Ghz on original firmware faster?

Installing and Using OpenWrt Network and Wireless Configuration
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First off, I have an TP-Link Archer C5 V1.2 which I did "upgrade" to an Archer C7 V2 with this tutorial a while ago ( https://blog.thesen.eu/wie-aus-einem-tp-link-archer-c5-ac1200-ein-archer-c7-ac1750-wurde/ ).

I just reverted back the original firmware, which is
Firmware Version: 3.15.1 Build 160616 Rel.44182n
Hardware Version: Archer C7 v2 00000000

With the original firmware I can achieve about 220 MBit via 5 Ghz WiFI, with Lede I only can reach about 120 Mbit. In both cases my mobile phone connects with 433 Mbit, but Speedtest is significanty slower on LEDE, even though I used the same settings (WiFi Channel, Bandwidth).

Did I forget a setting or is this a known problem?

I tried the official firmware and also [GCC 7.2 BUILD] Optimized TP-Link Archer C7 V2 AC1750 LEDE Firmware

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One thing I can think of is hardware NAT, which is not supported by LEDE unlike the stock firmware (I assume you were testing your speed using an Internet metering tool). NAT is performed when a local client access the Internet.

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Yup, I did several speedtest with this app: https://play.google.com/store/apps/details?id=org.zwanoo.android.speedtest&hl=de

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Did you try metering your performance using wired connection, just to confirm that WiFi is to blame?

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Reflashed Lede, just to be sure. LAN seems ok, albeit a tad slower, with 197 and 205 MBit. Also tested wireless again, huge difference with 113 Mbit and 195 Mbit.

Edit: When I have some time (after Zelda^^), I will try flashing different firmwares (DD-WRT, OpenWRT, Lede) to see if there is any difference regarding the 5 Ghz Wifi.

Edit2: Tested DD-WRT, seems wonky. Max connection to WiFI is 200 Mbit instead of 433 Mbit like stock or LEDE, speedtest gives 135 Mbit, a tad bit faster.

Edit3: Wow, going back from DD-WRT was a pain in the ***. Flashed OpenWRT and got 170 Mbit. Then I flashed the latest snapshop of LEDE, finally recieving 205 Mbit. Then back to latest stable of LEDE and still having 205 Mbit.

Not sure what happened here, maybe flashing around removed all traces of older configuration/firmwares, even though I always reset...

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I'm pretty sure by now that hardware NAT is the culprit; it is documented in the Wiki:

(...) OpenWrt firmware does not support the hardware NAT capability of these routers. Hence, the throughput between WAN↔LAN will be slower than with stock firmware. (...) If your internet connection is ⇐200Mbps you don't need to worry about this (maybe even up to 300Mbps). (...)

And in the corresponding thread according to extensive testing, most of the time expected throughput is around 200 Mbit, and this looks like what you're achieving on LAN. You can have a look at this thread about building your firmware with hardware NAT, experimental for the moment.

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Good to know. Although I have only 200 MBit cable internet (max speed is around 220 Mbit), so I am "safe" for now. But will keep in mind that I will have to revert to stock if someday I have an 400 Mbit or an 1 GBit connection.

Thank you for your support. I am happy with the current situation, LAN and 5 Ghz Wifi are only a tad bit slower, I can live with this. And if I upgrade my internet connection in the near future, I will revert back to stock then. Or buy a new router. WAN to LAN seems to be limited at 820 MBit. We'll see :slight_smile:

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@lupus You could also look at enabling Smart Queue Management (SQM) - Minimizing Bufferbloat. This might help you achieve better stability on high bandwidth usage.

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Good to see you got it straightened out. I have seen speeds of up to 240-280mbit DL, at close range on my C7 with LEDE. This with a Netgear A6200 USB adapter which is rated AC1200, on a Win 10 PC, doing a DSLReports test. I'm using it as my home router/AP for the house with 4 people doing various things. Currently running the 17.01.0 release.

So, as you found out, the C7 should go that fast if not a bit faster. Note that this is with no SQM. My cable service is 300/30mbit, but I see peak speeds up to 380, when hooking up directly with ethernet. Update: That, I should say, is equally fast going thru the C7, ethernet to ethernet. The C7 is not yet running out of CPU at that speed.

With the SQM on,the C7 gets CPU/IRQ limited quite a bit lower than that. With limits set for both for DL and UL, I see it getting maxed out delivering about130-135mbit, from a setting cap of 140/27mbit. Running Cake, and piece of cake mostly. Cake is supposed to be less CPU intensive than fc_codel.

Update, the above speed is eth in and eth out of the C7 with SQM on, I should report that using the 5Ghz wifi link, the saturation limit goes down to 100-120mbit. Seems that managing the wifi link takes some extra CPU resources. It will run at 130mbit, heck it will actually deliver about 220, but it's well into 0% idle time above 120, and I don't know how well Cake is doing it's job at that point.

In my case, I seem to have a pretty lag free DL, so I can run with the speed caps set to 0/27mbit, only controlling the UL, and that seems to work pretty well for me. I then get 220-240mbit downloading on the 5Ghz wifi link, seemingly a bit smoother, while the UL lag stays very flat. The IRQ/CPU load stays below100% downloading. YMMV... but that seems to be about where the limits of a C7 are.

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I thought SQM/Cake also automagically split the connection fairly (QoS), so that, for example, VoIP remains good despite huge downloads going on at the same time. If so, aren't you disabling QoS on your ingress, by putting a zero? Just curious.

edit: I think I see now. Your incoming bandwidth is so large that your connections do not compete, and thus, QoS serves no purpose. Is that so?

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When you enable a SQM, you set the "speed limit" of your download and upload to be slightly less than your full connection speeds. This allows the SQM algorithm to be the bottleneck, rather than some other part of your link, and it can then control the traffic. If you set "0", it doesn't set the limit to 0, it sets no limit on the traffic speed. I'm a bit unclear if it does nothing at all with that path when set that way, or is doing some kinds of work still. I have a crappy UL and a pretty good DL, and so it works for me to run with 0/28 or whatever.

The reason to not try to manage the DL, is in my case I have >300mbit, and a C7 just doesn't have enough power to handle that with the SQM on. (Now, if we could get the HW acceleration working, that might change things!) It can handle my 30mbit UL speed easily.

Even DL'ing a huge file, there's still UL ack'ing going on, so one may see DL improvement by managing the UL and not the DL. So even if setting the DL cap to 0 does completely disable the SQM, better UL might explain the slight improvement I still seem to see.

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Hello, I know that I will not help in your topic but I hope you can help me how you did the firmware download of tplink, (revert) how is the process not to brikear the routerplease, I am having the same problem and I want to revert the firmware openwrt, please and thanks

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