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I want to make an AP from a Linux PC with an USB Wi-Fi adapter.

My attempts until now weren't really successful; either the driver missed the AP capability feature, or the signal strength was negligible even from the next room.

I would be really glad to reduce the costly buy-try-throw cycle, anybody has a good experience with such a thing?

If it is impossible (for example the power is not enough on the USB bus), PCI card would be also okay (I've tried one with an Atheros chipset, but the signal strength was with it also negligible).

If it needs a little bit of SW/HW hacking, it is not a problem.

Ola Ström
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peterh
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  • It sounds odd that you'd find a PCI card with a "negligible" signal strength. So I suspect your notion of what is a good signal strength might need to be described in more details. In most cases the signal strength mostly depends on the antenna more than the card itself. – Stefan Nov 18 '15 at 15:32
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    @Stefan Ok. From around 50cm distance it has the same signal strength as the wifi of my neighbors (they are 10m distance, behind at least one concrete wall). I use the antenna I've got from the manufacturer with it, have a direct visibility with the device, and I've tried the antennas in every possible orientation. Maybe it is a bad card, but if it is so, it would be sooo happy if I shouldn't buy a similarly bad hardware again. These buy - doesn't work - throw out - money lost loops are very, very embarrassing. Warranty isn't always applicable, and has also administrative / postal costs. – peterh Nov 18 '15 at 18:10
  • @K7AAY It does not depend on the distro, specifying the distro would be an uneeded (misleading) part of the question. But I use Debian (Buster now and probably Stretch at the time). It depends on the kernel. I use recent stable kernels. My current experience is that the station mode works pretty well, but the AP mode still don't. Meanwhile I used other solutions for the problem, however I am still quite interested, what is going on the AP front in the Linux kernel. In my opinion, an AP should be able to do everything what we can do on an ethernet cable. – peterh Mar 18 '20 at 20:59
  • https://vitux.com/make-debian-a-wireless-access-point/ is excessively cheery to a skeptic, but have you tried it? And, when you refer to PCI, are you aiming at a mini-PCIe card to mount in a laptop, or a PCI bus card for a desktop? What WiFI HW do you have at present, BTW? – K7AAY Mar 18 '20 at 21:14
  • @K7AAY At the moment I use an old belkin usb (050d:845a). Earlier I tried numerous devices and the results were... well... not very good. I had luck if station mode worked. Many devices did not even have a working driver. Now the case is much better (nearly all the devices can work in station mode). The old belkin usb uses the staging driver r8712u, I have the most hope in it, although the driver does not yet follow the 80211 api in the kernel (it was developed by the manufacturer before that api appeared and nobody ported it to that). – peterh Mar 18 '20 at 22:37
  • @K7AAY Now I tried to set up the gnome network manager gui app. It says, "Connection myAp is not available because profile is not compatible with the device (the device does not support Access Point mode)". I tried also an unofficial driver at the time, which supported but was very weak signal and unstable. I've also tried windows from an virtual machine with direct path, so it worked, but it had many problems. – peterh Mar 18 '20 at 22:50
  • @K7AAY I've just checked the rtl8712 driver source in a current kernel. It seems supporting AP mode! But, if I try to set it, I simply does not happen. Somehow it should be sniffed, what a windows driver communicates with the usb port, doing the same with linux (in qemu, with usb directpath), and then comparing them, and fixing the driver. I would be soooo happy if I would have the time for that :-( – peterh Mar 18 '20 at 23:28
  • https://hardwarerecs.stackexchange.com/help/on-topic explicitly states in its next to last full graf: Questions asking about troubleshooting hardware or technical support for hardware may be on topic on (for Windows) Super User (and http://unix.stackexchange.com is the place to ask about this RTL8712 driver problem with Debian). I'd suggest incorporating the substance of the discussion into the question with [edit] then ask you to click [flag] and suggest to be moved there. Dang it, but since this has become a Debian-centric issue, I am over my head here. – K7AAY Mar 19 '20 at 16:39
  • @K7AAY Well, maybe the rtl8712 problems were offtopic here, but you asked it. My problem was at the time that I bought about 3 different usb wifi dongles and none of them worked. I also bought a pci atheros card, it worked but the signal strength was very low. Here the goal is only to find a pci or usb wifi device having a good-working linux driver. The actually used distro is particularly a non-issue in the question, because - as I've already explained - the problem roots in the drivers at the time. Now the chances seem better, but I would be still happy to make an AP from my home server. – peterh Mar 19 '20 at 16:46
  • @K7AAY Debian only integrates linux-compatible opensource softwares, including the linux kernel. Talking about a distro, instead of talking about a device with a good driver, is highly misleading (we are not talking about the important things). – peterh Mar 19 '20 at 16:49

2 Answers2

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The devices that have been tried are client devices. They have small low-power antennas/amplifiers as compared to WAPs which have high power/gain antennas/amplifiers. Which is why a hotspot from a mobile is not going to reach the next room reliably.

Rohit Gupta
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  • That is right and I know it. Although "next room" is a bit of relative thing: 1) there is still huge difference in the power of the client antennas 2) also the walls might be very thick or not, or being built from brick or reinforced concrete. Anyways, my home project is to build a mesh from an ad-hoc self-organising topology in l3 level of my home devices. It would be very funny and useful and... honestly... the fact that I simply can not set it up in any of my devices, despite that the hardware could do that... I can not say any really polite on my this experience. – peterh Nov 25 '23 at 09:47
  • I am suggesting that the hardware can not do it. The amplifier for receiving and transmitting will not have enough gain. – Rohit Gupta Nov 26 '23 at 04:44
  • The essence of my comment is that yes, it can. – peterh Nov 26 '23 at 10:53
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https://github.com/morrownr/USB-WiFi

This is a list of USB wifi adapters tested by the community.

Part of the same website but a specific list

https://github.com/morrownr/USB-WiFi/blob/main/home/USB_WiFi_Adapters_that_are_supported_with_Linux_in-kernel_drivers.md

Each one has extensive notes that are too long to copy and paste here.

https://github.com/morrownr/USB-WiFi/blob/main/home/The_Short_List.md

I recommend reading all the information before going out and buying anything.

Also contributing your experience to them so no one else buys bad devices.

cybernard
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