Module Apache mod_remoteip cause SSL Handshake failed (5) when load testing

I have Haproxy which load balance the traffic to two apache servers.
When I benchmark with apache benchmark tool I have no errors and everything works as expected.

But when I activate the proxy protocol communication between HAProxy and apaches I start having issues.

There are two scenarios

1- Load testing with less then 500 request/second everything works well.

2- Load testing with concurrent requests > 600. I start having SSL handshake failed (5) issues.

• Here is my HAproxy configuration:

   #---------------------------------------------
   # Global settings
   #---------------------------------------------
   global
   log 127.0.0.1 local0 debug
   chroot      /var/lib/haproxy
   pidfile     /var/run/haproxy.pid
   maxconn     3000
   user        haproxy
   group       haproxy
   daemon
  
   # turn on stats unix socket
   stats socket /var/lib/haproxy/stats
  
   #---------------------------------------------
   # common defaults that all the 'listen' and 'backend' sections will
   # use if not designated in their block
   #---------------------------------------------
   defaults
   mode                    tcp
       log                     global
       option                  tcplog
       option                  dontlognull
       option http-server-close
       option                  redispatch
       retries                 3
       timeout http-request    10s
       timeout queue           1m
       timeout connect         10s
       timeout client          1m
       timeout server          1m
       timeout http-keep-alive 10s
       timeout check           10s
   #---------------------------------------------
   # Servers sections
   #---------------------------------------------
   frontend XXXX:443
     bind XXX:443
     mode tcp
     use_backend https_front
  
   backend https_front
     balance roundrobin
     server XXX XXX check send-proxy
  

• My apache vhost conf:

  <VirtualHost *:443>
    ...
    ServerName XXXX
    RemoteIPProxyProtocol On
  

• My benchmark command:

   > ab  -c 1020 -n 9000  https://XXXX
    ...
   SSL handshake failed (5).
   SSL handshake failed (5).
   SSL handshake failed (5).
   SSL handshake failed (5).
   SSL read failed (1) - closing connection
   139921183344512:error:140E0197:SSL routines:SSL_shutdown:shutdown while in init:ssl/ssl_lib.c:2094:
  ...
  

I can not find any logs neither in haproxy nor in the apache logs. Did someone face the same issue before ?

Thanks in advance