Self-hosted KoBoToolbox randomly "shutting down" (504 error)

Following our conversation, as @stephenoduor mentions I ping you on the detailed topic about our problem. @Kal_Lam ; @stephenoduor; @ks_1

Here is the screenshot of the display message we are facing while connecting to Kobotoolbox, Enketo while the problem occurs.

Capture d’écran 2022-05-06 à 10.30.53

This problem can compromise the use of Kobo for the realisation of our project :’(
Thanks in advance for your help !