Hello ABG, thank you for your reply!
I added it to the blocks section:
and also to the ESP32 code:
But I ams till getting the same limitation.
I found this article ([SOLVED] Can't send payload > 23bytes(MTU setted to 128bytes) - #11 by carloss) that says that WriteStrings is STILL capped to 23 bytes (while WriteBytes is not).
Is that still the case? What options do I have to send a JSON string payload bigger than 23 bytes?
Thank you!

