WAF - AH00898: Error reading from remote server returned by /Microsoft-Server-ActiveSync

Question

Hi All, Not having any problems with the Active Sync Clients but noticing a lot of issues filling up the WAF logs every few minutes... wanted to check what the issue is?

httpd[3749]: [proxy_http:error] [pid 3749:tid 4103859056] (70007)The timeout specified has expired: [client 209.XXX.XXX.XXX :3622] AH01102: error reading status line from remote server 10.XXX.XXX.103 :443 
 
 httpd[3749]: [proxy:error] [pid 3749:tid 4103859056] [client 209.XXX.XXX.XXX :3622] AH00898: Error reading from remote server returned by /Microsoft-Server-ActiveSync 
 
 httpd: id="0299" srcip=" 209.XXX.XXX.XXX " localip=" 162.XXX.XXX.XXX " size="434" user="-" host=" 209.XXX.XXX.XXX " method="POST" statuscode="502" reason="-" extra="-" exceptions="SkipURLHardening" time="300143092" url="/Microsoft-Server-ActiveSync" server=" mail.XXXXXXXXXX.COM " port="443" query="?Cmd=Ping&User= DOMAIN %5C USERID &DeviceId=SEC14140F09XXXX&DeviceType=SamsungDevice" referer="-" cookie="-" set-cookie="-" websocket_scheme="-" websocket_protocol="-" websocket_key="-" websocket_version="-" uid="XUwdYqL3eg4AAA6lpigAAAAD" 
 
 httpd: id="0299" srcip=" 209.XXX.XXX.XXX " localip=" 162.XXX.XXX.XXX " size="46" user="-" host=" 209.XXX.XXX.XXX " method="POST" statuscode="200" reason="-" extra="-" exceptions="SkipURLHardening" time="218352129" url="/Microsoft-Server-ActiveSync" server=" mail.XXXXXXXXXX.COM " port="443" query="?Cmd=Ping&User= DOMAIN %5C USERID &DeviceId=SEC14140F0XXXX&DeviceType=SamsungDevice" referer="-" cookie="-" set-cookie="X-BackEndCookie=S-1-5-21-3768258204-2388712022-2097333300-1156=u56Lnp2ejJqBnJ3MmpnGzszSnpzPmtLLz8rK0p3Hm57Szs/Ix53Ny57OyZydgYHNz87G0s/G0s/Iq87Mxc7OxcvG; expires=Sat, 07-Sep-2019 13:11:49 GMT; path=/Microsoft-Server-ActiveSync; secure; HttpOnly" websocket_scheme="-" websocket_protocol="-" websocket_key="-" websocket_version="-" uid="XUweoqL3eg4AAA6lpiwAAAAv" 
 
 id="0299" srcip=" 209.XXX.XXX.XXX " localip=" 162.XXX.XXX.XXX " size="1580" user="-" host=" 209.XXX.XXX.XXX " method="POST" statuscode="200" reason="-" extra="-" exceptions="SkipURLHardening" time="366303" url="/Microsoft-Server-ActiveSync" server=" mail.XXXXXXXXXX.COM " port="443" query="?Cmd=Sync&User= DOMAIN %5C USERID &DeviceId=SEC14140F09XXXXX&DeviceType=SamsungDevice" referer="-" cookie="-" set-cookie="X-BackEndCookie=S-1-5-21-3768258204-2388712022-2097333300-1156=u56Lnp2ejJqBnJ3MmpnGzszSnpzPmtLLz8rK0p3Hm57Szs/Ix53Ny57OyZydgYHNz87G0s/G0s/Iq87Mxc7OxcrO; expires=Sat, 07-Sep-2019 13:11:51 GMT; path=/Microsoft-Server-ActiveSync; secure; HttpOnly" websocket_scheme="-" websocket_protocol="-" websocket_key="-" websocket_version="-" uid="XUwffqL3eg4AAA6lpi0AAAAw"