wifi-ble coex: rapidly send UDP packets causes BT disconnections when device is physically moved

Hello community,

I am stumbling into a very strange phenomenon.

I'm using a nRF7002DK running a custom firmware that reads data from a bunch of sensors and forwards these data via UDP. The connection is achieved via Wi-Fi, and in my while(true) cycle I just read data from the sensors (it takes about 10ms), organize my data structure (about 500 bytes), and send via UDP.

I have set up the whole wifi-ble coex interface in my firmware such that I can also communicate with a couple of nRF5340DK that are running the Peripheral-UART sample. My BT-related firmware is based on the multi-NUS sample.

Everything seems great: I can reliably stream UDP packets and have both the Peripheral-UART steadily connected via BT (I'm not exchanging data yet via BT).

The really odd thing that happens, as per the title, is that I start to see BT disconnections as soon as I physically move the nRF7002DK. UDP packets are not affected at all.

Here is the log of my custom fw in the 7002dk



This odd behavior stops (meaning it NEVER shows) as soon as I comment out the line in my while(true) that actually sends data via UDP. 

I was barely able to find some info about Disconnection Reason 8 and 62 but nothing related to some sort of problem in the coex setup.

Honestly, I have no idea about where to start: if it was just a FW problem, it should be seen consistently; I don't even think it's an HW problem since I'm using the nRF7002DK and not some custom boards

Any hints on what to start looking for?

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