Networking issues during printing

sigxcpu

So, I have this issue since upgrading to 1.19(.2).
Some time after a print starts, there is no network connection at all to the printer (no telnet, no HTTP, no ping).
After the print is done, the connection is restored.

This doesn't happen to all prints but most of them. Yes, I've read about CPU overheating but:

this never happened on 1.18
the printer didn't move or change its configuration or physical layout since 1.18
the AP didn't move or change since 1.18
there is no higher WiFi noise since 1.18 because I leave in the country-side so the number of neighbor APs and devices is pretty constant
the electronics are ventilated by a 120mm fan that runs at 100% during printing and enclosed in a big space (50x50x10cm)
it never happened during the summer (~36-38 degrees room temperature). For comparison, current room temps are in the 22-24 degrees C range

The only big change (that I know of) since 1.19 is the WiFi firmware right?

dc42

Thanks for the feedback. The "no ping" bit is surprising, because pings are handled on the WiFi module without the Duet main processor being involved.

What RSSI does does M122 report?

What microstepping are you using, and what are your steps/mm?

sigxcpu

WiFi signal strength -62dBm

M92 X160 Y160 Z2133.33

M350 X16 Y16 Z16 E16 I1
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I don't think this is a WiFi signal caused disconnection, unless something changed in firmware regarding sensitivity, because, again, it is the exact same setup as it was before.
Maybe useful, but the upload speeds are between 600 and 900KB/sec, so I assume the signal is fine.
It is not such a big deal, but sometimes I tweak stuff during the print and I don't want to be forced to buy a PanelDue because of this.

Unfortunately, my last print did this 2 days ago and I've forgot to take M122 right after the connection was established. Yesterday it was a power cut and the thing rebooted, so I've lost the "reason" or whatever you are looking for after reconnect.

Just to be clear, it reconnects after the print is done. There is no reboot required.

dc42

When you say it reconnects after the print is done, is that just by pressing Connect in Duet Web Control?

If you try to connect again while it is printing, do you get any particular error message when it fails, for example a json parse error?

sigxcpu

It reconnects by pressing "Connect", of course. All the server apps (web UI, ping, telnet, ftp) start to work by magic when the print is done.

I don't remember, but I'm pretty sure it is a timeout message. The printer's IP is not reachable on any port and protocol. I am and IT guy at the core, so I am 100% about "unreachable". It simply stops being there from the network point of view.
What I didn't check is if the AP still sees it joined at all during the down time. I will do that next time.

I've remembered a maybe important bit: it didn't happen on short prints (<1 hour) and I don't know when it happens on longer prints because I find it dead when I check occasionally.