Have to restart Haproxy every few minutes - haproxy

Question

(Ubuntu 16.04, 6 cores, 24GB Ram, Haproxy 1.8.0)
I've read so much about how easy haproxy is, so we set it up, did some basic testing / load testing and things looked good. Put it into production last night, things look good, until we start getting production traffic. I have to restart haproxy every few minutes b/c sites just stop responding. The stats website isnt showing me any stats that look alarming, and the machine is hardly using any resources.
Basically here is what we see - We restart haproxy, everything works great, then a few minutes later we have to restart it again (under production load).
Looking at the stats page I see the backend gets to around 50k sessions and then stuff just stops working.
Here is my config, can you check it out and help me understand how I should tune it?
global
log 127.0.0.1:22514 local2 debug
chroot /var/lib/haproxy
stats socket /run/haproxy/admin.sock mode 660 level admin
stats timeout 30s
user haproxy
group haproxy
daemon
# Default SSL material locations
ca-base /etc/ssl/certs
crt-base /etc/ssl/private
# Default ciphers to use on SSL-enabled listening sockets.
# For more information, see ciphers(1SSL). This list is from:
# https://hynek.me/articles/hardening-your-web-servers-ssl-ciphers/
ssl-default-bind-ciphers ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES:ECDH+3DES:DH+3DES:RSA+AESGCM:RSA+AES:RSA+3DES:!aNULL:!MD5:!DSS
ssl-default-bind-options no-sslv3
tune.ssl.default-dh-param 2048
defaults
log global
mode http
option httplog
option dontlognull
option http-server-close
timeout connect 50000000
timeout client 50000000
timeout server 50000000
maxconn 80000
errorfile 400 /etc/haproxy/errors/400.http
errorfile 403 /etc/haproxy/errors/403.http
errorfile 408 /etc/haproxy/errors/408.http
errorfile 500 /etc/haproxy/errors/500.http
errorfile 502 /etc/haproxy/errors/502.http
errorfile 503 /etc/haproxy/errors/503.http
errorfile 504 /etc/haproxy/errors/504.http
frontend loadbalanced_main
log global
bind *:80
mode http
redirect scheme https if !{ ssl_fc }
acl web1 hdr(host) -i -m sub 1.a.com
acl web2 hdr(host) -i -m sub 2.a.com
acl web3 hdr(host) -i -m sub 3.a.com
use_backend ordweb1 if web1
use_backend ordweb2 if web2
use_backend ordweb3 if web3
default_backend loadbalanced_nodes
frontend loadbalanced_main_ssl
log global
bind *:443 ssl crt /etc/ssl/private/a.com.pem crt /etc/ssl/private/b.com.pem
reqadd X-Forwarded-Proto:\ https
acl web1 hdr(host) -i -m sub 1.a.com
acl web1 hdr(host) -i -m sub 1.b.com
acl web2 hdr(host) -i -m sub 2.a.com
acl web2 hdr(host) -i -m sub 2.b.com
acl web3 hdr(host) -i -m sub 3.a.com
acl web3 hdr(host) -i -m sub 3.b.com
use_backend ordweb1 if web1
use_backend ordweb2 if web2
use_backend ordweb3 if web3
default_backend loadbalanced_nodes
backend ordweb1
mode http
redirect scheme https if !{ ssl_fc }
balance roundrobin
option forwardfor
http-request set-header X-Forwarded-Port %[dst_port]
http-request add-header X-Forwarded-Proto https if { ssl_fc }
option httpchk HEAD / HTTP/1.1\r\nHost:localhost
server ordweb1 10.154.18.100:80 cookie check
backend ordweb2
mode http
redirect scheme https if !{ ssl_fc }
balance roundrobin
option forwardfor
http-request set-header X-Forwarded-Port %[dst_port]
http-request add-header X-Forwarded-Proto https if { ssl_fc }
option httpchk HEAD / HTTP/1.1\r\nHost:localhost
server ordweb2 10.154.18.8:80 cookie check
backend ordweb3
mode http
redirect scheme https if !{ ssl_fc }
balance roundrobin
option forwardfor
http-request set-header X-Forwarded-Port %[dst_port]
http-request add-header X-Forwarded-Proto https if { ssl_fc }
option httpchk HEAD / HTTP/1.1\r\nHost:localhost
server ordweb3 10.154.18.9:80 cookie check
backend loadbalanced_nodes
mode http
redirect scheme https if !{ ssl_fc }
balance roundrobin
option forwardfor
http-request set-header X-Forwarded-Port %[dst_port]
http-request add-header X-Forwarded-Proto https if { ssl_fc }
option httpchk HEAD / HTTP/1.1\r\nHost:localhost
cookie SRV insert indirect nocache
server ordweb1 10.154.18.100:80 check cookie ordweb1
server ordweb2 10.154.18.8:80 check cookie ordweb2
server ordweb3 10.154.18.9:80 check cookie ordweb3
listen stats
bind *:1936
stats enable
stats uri /
stats hide-version
stats auth nope:blah