Strange 522 error

Starting a few hours ago we are experiencing strange 522 timeout errors from Milan cloudcenter ray-id 5e25c5e1884c0f7a and involving all our sites on different servers.
What is strange is that these errors happens only if we open these sites from telecom italia ip addresses.
If we use other providers (italian and outside italy) everything works so this has nothing to do with web servers configuration.
Colud this possibly be some routing problem between telecom italia and cloudflare?