Hang with Pico W when using a W5500 and WiFi at the same time.

[earlephilhower]

Discussed in #2149

^{Originally posted by rpineau May 7, 2024}
Fisrt some background :
I have a system where a "rotator" Arduino Due controls an observatory dome and a "shutter" Arduino Due which control said dome shutter.
The "rotator" arduino due use a W5500 to connect to the local network and both Due communicate with each other using XBee modules:

Local network <----> [W5500/Rotator Due/XBee] <-----> [Xbee/Shutter Due]

I'm now working on replacing these with Raspberry Pi Pico W and want to use the WiFi connection to replace the XBees.
I ported the code to the Pico W. Core 0 is for communications (Ethernet, WiFi and serial) and Core 1 takes care of the motion (it drives
stepper motor using the AccelStepper library) :

Local network <----> [W5500/Pico W/WiFi] <-----> [WiFi/Pico W]

The problem(s):
When disabling WiFi on the "rotator", Ethernet works fine and all is good.
But as soon as I want to add WiFi problems starts and the WiFi connections between the 2 Pico W keeps failing.
It also seems to create some timeout on the W5500 side (pinging the "rotator" Pico W from a machine starts failing).
To try to figure out the issue I made 2 small test firmware that only use the ping function.
As far as I can tell the issue comes from the Pico W that also has the W5500 . After a bit of time it locks up in the wifi ping function.
I also try with just WiFi between the 2 Pico W. This is more stable but I see a lot of drops at the beginning and then latter on (not repeatable timing as far as I can see).
So the question is .. Am I doing something wrong or is this a "bug" and the Pico W can't do Ethernet and WiFi at the same time ?
The test code can be found there :

https://rti-zone-files.s3.amazonaws.com/test-rp2040.tgz

Thanks for any insight.
Rodolphe