UPDATE:
The ORDER of certain wireless config lines in the INI can cause the ‘Network I/O’ errors.
It was the ROOT cause of our Network I/O errors all along. Our ‘Network I/O’ issues did not happen until ThinOS 8.6.
It turns out that the older ConfGen tool generated the INI file with the ‘Device-wireless’ line at the END. (tested with 7.4) Newer versions generate the same line AT THE BEGINNING of the wireless section. (tested with 8.5)
Example:
From 2019
IEEE8021X=yes network=wireless access=WPA2-ENT eap=yes eaptype=EAP-PEAP peapmschapdm=MyDomain.com peapeap=EAP-MSCHAPV2 \
peapmschapun=UserID1 \
peapmschappwdEnc=!!!!!!!!!!!!!!!!!!!!!!!!!!!
Device=Wireless Mode=Infrastructure SSID=”OurSSID” RoamSensitive=-69dbm PreferBand=5G DisableWLAN=EnetUp Priority=”MySSID”
vs
2022
Device=Wireless Mode=Infrastructure SSID=”OurSSID” RoamSensitive=-69dbm PreferBand=5G Priority=OurSSID DisableWLAN=EnetUp
IEEE8021X=yes network=wireless Profile=OurSSID access=WPA2-ENT eap=yes eaptype=EAP-PEAP peapmschapdm=MyDomain.com peapeap=EAP-MSCHAPV2 \
peapmschapun=UserID1 \
peapmschappwdEnc=NNEH6MFCIHBCN6ACPGAAFFLIDFLL
Changing the order alone will not resolve the issue. We had to add “Device=NIC Default=WLAN” to the devices INI files to trigger some odd change within the device. Once we did this, the devices no longer lost their default gateway after 4-5 hours of activity. You can also just manually change the Default Gateway locally on the device once to “fix” the issue.
Another interesting issue is that you cannot manually change the Default Gateway in any of the ThinOS 8.6.x builds. Try it yourself. Change the default gateway in the Network settings…go back and see if it sticks. It will not. It may just be a GUI bug, but something odd is going on here.
Dell Support is aware of this, but ThinOS 8.6 is EOL and not being updated. So this workaround will have to do for the thousands of Dell 5040s we have under warranty until 2024. I thought I’d share my finding so that I could help someone else with this odd issue.