Environment health has transitioned from Warning to Ok to Warning

Hello...

Several times a day we receive messages like the following:

• Environmental health has transitioned from Ok to Warning. No data received from 1 out of 3 instances. 33.3% of the requests to the ELB are failing with HTTP 5xx. Insufficient request rate (1.5 requests/min) to determine application health (5 minutes ago).

• Environment health has transitioned from Ok to Warning. 1.0 % of the requests to the ELB are failing with HTTP 5xx (3 minutes ago).

But this happens very fast and we can't see the cause of the problem.

We have looked at the logs and we have not found relevant information either.

I appreciate if someone can guide me on how to resolve this notification Thanks in advanced