Wifi Client advice

Ian

I am hoping that someone can advise me: I run remote pi 4 2gb with the latest moodlebox image. The pi gets turned on and off by the manager in the remote area but he/she has no access to other admin functions so the time is not set at startup (no RTC). I have noticed that fewer and fewer clients can access the moodlebox - am now on 4 to 6 maximum which is way down on the 12 to 15 I started with. When I log in as admin, I see a number of devices logged into moodle (moodlebox dashboard) who are not present. Could it be that the DHCP clients are not being released as the start time is always being reset? If this is unlikely, could someone advise what I should be looking at as I cannot operate with only a few students accessing the device.

Ratna

Ian Difficult question. Since I don't have a set up to reproduce it, all I can do is to guess.

I don't think the number of wireless devices registered as connected but are not transmitting will reduce the number of new devices accepted. The reason is that this maximum number is not limited by software but a hardware limitation. It is the maximum number of devices with which RPi has enough power to actively communicate. (The relevant discussions from RPi have been pointed out in this forum.)

I assume that the number of stale devices are not very high. How many? Say, in a case where only 5 devices could connect, can you see 10 stale devices?

Ian

Ratna Thanks Ratna. I confess to being a bit confused. The ip adress allocation list is way beyond what we would need (ie from 001 to 256). I do not know why the device is refusing entry to more than 5 or 6 users. I am using the official power supply so it shouldn't be that. Moodle should not have a limit on access. I am using a 64gb sd with 13gb free so memory & space should not be the limit. The content accessed is varied with some large video material (130mb) but I had no issues when I used the pi3B with moodlebox version 5. I really am grasping at straws.

Ratna

Ian Hi, confused? May be not. But you are talking of at least three things.

Ian

Ratna Thanks. Some of the individual connectivity problems have been solved. Due to government monitoring many people here run vpn's. It would appear that the vpn setup does not support non-regular web addresses and this causes them to hang (i have tried various versions of moodlebox.home/ moodle.box etc)- so the problem is not entirely the pi! I will do more checking with each individual who has had connectivity problems. Now to start again on assessing the number of clients at the site.
By the way, the moodlebox dashboard shows connected devices even after disconection and after the dhcp lease time has expired - but I don't think this is causing any issues with connectivity.
I am considering this thread as solved.

Nicolas

Ian By the way, the moodlebox dashboard shows connected devices even after disconection and after the dhcp lease time has expired - but I don't think this is causing any issues with connectivity.

Indeed, this is not an issue: all the IP addresses remain reserved for 4 hours and there are more than enough addresses available (exactly 245!) for this to be no problem. The machines that are shown in the interface are the ones that still have a reserved address (but may have disconnected).

This is a feature, not a bug, because it is important that a person who disconnects (e.g. accidentally) can find the same IP address after reconnection.

Ian

Sorry to bring the topic up again. Here is the same post I have put on the RPi forum:
I am running a Moodlebox for "offline" lessons where students have no internet access. I was running the Pi 3B+ and had 11 students (most students in one place) logged in via wifi watching instructional videos.
I "upgraded" to the Pi 4 thinking the extra ram would enhance the user experience. Now only 5 users can log in at a time - when number 6 tries to join the whole system crashes!
I have been testing at home: Same image on a 64gb micro sd card - one in a Pi 3B+ and one in a Pi 4 2gb. I am using the official power supply on both.
I can log in 7 devices to the Pi 3 and all are running fine - all watching instructional videos. (My limit is 7 because that is all of my wifi enabled devices)
On the Pi 4, I get 5 watching videos and the sixth causes it to crash. I have to restart the device because it seems to freeze - no access for anyone.
My problem is I bought 10 Pi 4s and have another 20 being imported for a specific project! If I cannot solve this I have a real problem.
Please advise if this is a software or a hardware issue.
And a fix if possible.

Nicolas

Ian The situation has not evolved. This issue is not specific to MoodleBox. As already noted elsewhere, here's the forum thread to lobby and/or contribute to promote fixing this issue: https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=241223&start=25#p1472522.

See also the github issue: https://github.com/raspberrypi/linux/issues/3010.

Closing this thread. Please continue discussion here if really needed: https://discuss.moodlebox.net/d/36-low-number-of-concurrent-connected-users/43.