Luca,
Apache/2.4.18 (Win64)
10.114.119.* are the clients machines, 10.114.43.102 and 10.114.43.103
are the app servers
yes i can see 502 in the httpd access log but all are related to a
specific ajax we are using in our application, in other words it's not
related to the disconnection issues we are facing
from application server i cannot see any error, but from the client
machine the session expired