Another 522 error post

I’m having random errors wtith 522, most are reported by users in Chile, haven’t been able top reproduce it myself.
Keep alive is configured.
Ipv4 ips for cloudflare are whitelisted.
No ipv6 configuraed for my domains or network.
I did read the tips on the site, just expanded the keepalive time for the last site that got reported.
No rule in iptables blocking cf on the server side, and firewall has the proper whitelist.
The biggest isssue is that is not consistent, last time, I got a report, it only lasted a few minutes,
but having sometimes this answer is awfull for uptime and company image.

I am seeing same behavior with Brazil and Letonia access. Timedout problems.