Hardware mod tutorial: Replace wifi cards on Linksys WRT-1900AC v1

Might fix various issues. Somebody fixed pretty big problems. Probably still doesn’t support WPA3.

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WRT1900ACv1 - supports WPA3 in DD-WRT - I have not tried a recent build of OpenWrt on it, but I suspect a Snaphot build should work.
WRT3200ACM - nothing will get WPA3 working on its wifi chip - just trying to is enough to disable wifi and will require a restore from backup to get wifi working correctly again.

Could try disabling hwaccel.

Which cards did you go with? MediaTek AX ones?

@nickant
I don't know. Open it and see if the wifi is on a separate board.

@neheb
Too little, too late. I did this mod a month ago and it solved all my mwlwifi problems permanently.

@Borromini
No. Atheros AR9380 for 5GHz and AR9285 for 2.4GHz. Both work with ath9k.

Hello,

Attention, I have just taken a wrt1900ac v2 (cobra), I wished to "modder" it with another wifi card.

And surprise, the wifi card is built into the motherboard, so not all models are supported.

Fortunately, I already have the wrt1900ac v1, so I'll be able to check whether this tutorial is true.

Best regards,

Oh the guy that fixed up the driver. Welcome.

Unfortunately, I no longer own my v1 or v2 so I can’t be of help in this thread.

Is there any concurrent Wifi 6 or Wifi 6E cards available that could work in OpenWRT?

I've seen something about 6E working on OpenWRT on Reddit, but not sure in that case what is the best selection of cards for 4 antennas? This could eventually turn WRT1900AC into a fully working Wifi 6(E) router.

Edit: those are examples of such cards:
1.

2.

M.2 cards with mt7916 or qcn9074 would be the only 'generic' alternatives (with mt7916 support probably being further along/ more dependable at this point).

AsiaRF changed their URL structure, so links from above are missing.
Replaced by all Mini-PCIe cards:

Anybody knows can any of those Wifi 6(E) cards work on OpenWRT?
My only concern is that there might not be enough power on the slots or the cards get way too hot.

You may try to find the devices in the official linux wireless list to see if they are supported or not:
https://wireless.wiki.kernel.org/welcome

Not enough power or not enough cooling is a valid concern.
Try using a very low-power card for the 2.4GHz band or remove it completely if you don't need it.
I don't think there's more than one 3.3V power supply for the entire router so you could monitor 3.3V on the serial port pin with an oscilloscope to see if there are any problems.
For cooling, you may try to install back the original heatsink over the new wifi cards, with thermal pads or just grease depending on the remaining space.

I'd suggest to sharpen your pencil and recalculate if something like https://git.openwrt.org/?p=openwrt/openwrt.git;a=commitdiff;h=e7c399bee677e9bac66e1bea697aefb8d828edfe might not be a better choice over all.

The best router is the one you have. :wink:

Correct, as long as it meets your requirements in its current (factory-) state. Once you start investing into an old horse that already smells bad, you might want to reconsider your options.

Look, I've been in your shoes ~15 years ago with the Asus WL-500gP v1… Nice router, but coming from the factory with a defective BCM4318 card (they chose the wrong resistance for one SMD resistor in a batch of devices, resulting in very bad range). Replacing the BCM4318 card with an Atheros (ath5k) card was a common procedure back then (meaning it was known working, there even was a dedicated OpenWrt image for this hardware mod). So I bought the components (ath5k mini-PCI card, a second pigtail and RP-SMA antenna). The procedure went fine, the router was now working better than before - but I didn't use it long beyond that, a TL-WR1043NDv1 was calling and its natural successor. So while my replacement was a roaring success, the investment was still more of less 'wasted', as I didn't continue to use it long beyond that (faster SOC and more flash wanted, let alone 802.11n support).

In your case, you're spending around half the price of what the aforementioned device would cost you on components (self-imported, relatively long lead time). Most cards these days come in the M.2 form factor, you'd need mini-PCIe - so extra care (and a monetary markup) needed while ordering to get a mini-PCIe one (or a mini-PCIe to M.2 riser, which also costs money and might challenge your mounting clearance). Pretty much all wifi6 cards no longer come with the customary I-PEX/ U.FL antenna connector, but ship with a MHF4 connector instead, meaning you'd probably have to replace the pigtails between card and antenna as well (given the case integration of the original antennas, that might result in some case modding and probably needing new antennas as a side effect as well). Just these additional hardware requirements (pigtails and antennas, count on average roughly a fiver each) push your expense already pretty close to what a filogic 830 router would cost you.

Now let's take a look at the risks involved:

  • Mediatek wireless cards are pretty much exclusively used on little-endian devices, but mvebu is big-endian - it wouldn't be the first time that this would cause issues (yes, technically this would be a driver bug in need of fixing anyways, but unless anyone tests it… (yes, cz.nic is offering this for their Turris Omnia, so maybe you're in luck, maybe)).
  • these cards (all wifi6 ones) have serious power requirements, 10 watts over the 3.3V line (this is beyond mini-PCIe/ M.2 specs and might damage your router, if it can't supply that much - maybe immediately, maybe over a few weeks)
  • as a consequence of the above, these cards are running hot, meaning a rather large heatsink is mandatory, depending on the ventilation also an active fan. Your task to make it fit (and cope with the fan noise).
  • DTS changes required, until the end of time - you may also experience side effects from the old mwlwifi integration (calibration data extraction, sysupgrade helpers, etc.) - it's just an 'unsupported' combination, meaning you're your own developer and supporter.

Now let's look at the elephant in the room.
The factory setup of the WRT-1900AC v1 comes with two 4x4 cards on a custom (single) PCB, but only four external antennas - this means the rf signals of one 2.4 GHz chain (card) and one 5 GHz chain (card) are muxed together, leading to each of the antennas transmitting 2.4+5 GHz.
What's your solution to this?

Matching signal muxers are hard to come by (and relatively expensive), so probably not going to happen.

This leaves you with two alternatives:

  • one mt7915 DBDC card, effectively leaving you with 2x2 for 2.4 GHz and 2x2 for 5 GHz, not a very satisfactory solution - as you could get the same result with a 15 EUR dap-x1860/ covr-x1860/ wsm20.
  • two 4x4 mt7915 cards (without DBDC), you now have to mount four additional antennas into the case - and make sure to retain enough distance between them for Mu-MIMO to work.

Is this all possible, yes - is it sensible or economically viable, no. If you take a look at the resale value of stock WRT-1900AC routers on the used markets, this is probably even less sensible.

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since when is mvebu big endian?

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@slh I'm not exactly sure who are you replying to. Me, or @deeddy .

I'm not using wifi6 cards and I probably never will. I renovated my apartment 5y ago and I have cat5 ethernet in all rooms. There's really no need for more than .11n for mobiles, as they are used mostly for browsing. The only reason to change my router now would more RAM, in which case I would probably buy a Turris Omnia, or a dual-ethernet SBC and a gigabit switch.

BTW, how is that mwlwifi driver working after the recent patch? I still have a WRT-1900ACS that is not wifi-upgradeable.

There is no need for any devicetree modifications. The wifi is on PCIe. PC buses had plug-and-play detection and autoconfig since ISA.

@neheb mvebu can run in both modes, but it requires both kernel and OpenWrt to be built the same way. I read somewhere that big-endian was supposed to be faster for network applications because TCP/IP is BE. I never tried. I didn't even try thumb mode.

probably needs bootloader too. I assume other complexities as well. Anyway for all intents and purposes, it's little.

Now I wonder if my WRT1900ACv2 can have similar replacement....