Haproxy 504 error

[admtpu]

I have used haproxy to do reverse proxy for a lot of my web.

I use vm to host websites, websites using ssl of cloudflare.
Web sites with low traffic, I configured haproxy without any problem, everything works very well.
There is only 1 high traffic site. I cannot successfully configure haproxy, cloudflare reports 504 errors.
I switched over to the squid, all working normally.
I don't know where I got it wrong.

# Automaticaly generated, dont edit manually.
# Generated on: 2019-03-29 02:21
global
	maxconn			1000
	stats socket /tmp/haproxy.socket level admin 
	gid			80
	nbproc			1
	hard-stop-after		15m
	chroot				/tmp/haproxy_chroot
	daemon
	tune.ssl.default-dh-param	2048
	server-state-file /tmp/haproxy_server_state

listen HAProxyLocalStats
	bind 127.0.0.1:2200 name localstats
	mode http
	stats enable
	stats admin if TRUE
	stats show-legends
	stats uri /haproxy/haproxy_stats.php?haproxystats=1
	timeout client 5000
	timeout connect 5000
	timeout server 5000

frontend http-merged
	bind			10.0.0.2:80 name 10.0.0.2:80   
	mode			http
	log			global
	option			dontlognull
	option			dontlog-normal
	option			log-separate-errors
	option			http-keep-alive
	option			forwardfor
	acl https ssl_fc
	http-request set-header		X-Forwarded-Proto http if !https
	http-request set-header		X-Forwarded-Proto https if https
	timeout client		30000
	acl			abc	var(txn.txnhost) -m sub -i abc.com
	acl			abc1	var(txn.txnhost) -m sub -i abc1.com
	http-request set-var(txn.txnhost) hdr(host)
	http-request set-header X-Forwarded-Proto https  if  abc1 
	use_backend abc_ipv4  if  abc 
	use_backend abc1_ipv4  if  abc1 

backend abc_ipv4
	mode			http
	id			10100
	log			global
	timeout connect		30000
	timeout server		30000
	retries			3
	source ipv4@ usesrc clientip
	server			litespeed 192.168.9.112:80 id 10101 check inter 1000  

backend abc1_ipv4
	mode			http
	id			10110
	log			global
	timeout connect		30000
	timeout server		30000
	retries			3
	source ipv4@ usesrc clientip
	server			litespeed 192.168.13.119:80 id 10109 check inter 1000  

[PiBa]

@admtpu
Maybe try and increase the client and server timeouts from 30000 milliseconds to something longer.?

[admtpu]

@PiBa Ok, I increased the time and it works well