Number of wifi clients?

ralfkrause

Hi,
a friend in my Moodletreff group found that he can‘t connect more than 15 clients to the MoodleBox 2.5.0. Using the Version 2.4.1 there were no problems with 25 clients.

How can I check my MoodleBox? Where does the MoodleBox save its client data? Is the client data saved in RAM or is it saved on the sd card?

Best regards, Ralf

Nicolas

ralfkrause I'm suspecting that this is maybe a hardware issue, because nothing was changed related to Wi-Fi config in version 2.5.0 since 2.4.1 (see the release notes).

The new RPi 3B+ is rather picky with the power supply (see eg here and here): if the power supply is not good enough (or if its cable is too long or with bad quality), some problems can occur, and the limitation of the number of Wi-Fi client is one of them. You can see this if the red LED goes off; the RPi 3B+ becomes unstable. I got several feedbacks that confirm this. Please check with your friend whether he has also changed his RPi model.

ralfkrause Where does the MoodleBox save its client data?

Client data is available in this file, on the SC card: /var/lib/misc/dnsmasq.leases.

Ratna

Hi Nicolas
Provided that the power supply is good enough, what is the limiting factor for the number of Wi-Fi clients that can be connected?
I see that the wireless network uses a /24 network. So 253 is the theoretical maximum. Do you have any numbers from experience?

Nicolas

Ratna The limiting factor is the hardware: the Raspberry was not designed as a high-performance wireless access point, and cannot handle too many concurrent Wi-Fi clients, and this is the only real limiting factor (DHCP is not).

I've made some live tests. The max Wi-Fi clients I've had was 29. I expect that a sensible real life max number is around 25 clients, just like classic Wi-Fi home routers.

Ratna

Hi Nicolas

Thanks for the number. I hoped, twice as much could connect, with a performance hit. In my planned application the speed can be very low, as long as the connection is stable. I see, it is not going to work that way.

I must put a wireless mesh in the lab. (Kidding, wireless is not my department.) But this discussion reminded me the off-line capabilities of Moodle Mobile. I will try that - once I get the chance.

FontaBox

We made tests with two systemes
OpenWrt and our picture of EPSBOX

We had measured the same results

Pi 3B accepts 17 linked simultaneous clients
Pi 3B + and 4 B only 17 clients

Even with resources used in only 15 %

Therefore to go on has make court with our EPSBOX and have more linking in simultaneous (our class are has + of 30 pupils)
I was forced to link a nano-navigator in RJ45 in AP mode in front of my Pi.

Knowing that even a nano navigator accepts only 32 connections simultaneous (Source constructor TPLINK)
he has needed to play with 2 SSID

just for information
sorry for my poor english

François
EPSBOX project

Ratna

FontaBox I am having difficulties in understanding you. The cause is not the language, I believe, I do not know the products you are referring to.

What you are saying is, you have tested RPis with systems similar to https://moodlebox.net/, which convert the RPis to wireless hotspots. And in none of those experiments you could connect more then 17 wireless devices to them?

Which RPi modles were they: 3A, 3B, 3B+ or 4B? What are the systems? https://openwrt.org/ ? Or its derivatives? Which ones? http://epsbox.free.fr/ (no english translation?)