Log file filling up quickly

In under a 24 period I have a logfile that fills up with this message:

2021:02:18-09:51:17 ast-thr-utm-001 httpproxy[16699]: id="0001" 
severity="info" sys="SecureWeb" sub="http" name="http access" 
action="pass" method="CONNECT" srcip="172.17.17.2" dstip="10.1.10.2" 
user="" group="" ad_domain="" statuscode="200" cached="0" 
profile="REF_HttProContaInterNetwo2 (Default Filtering Group)" 
filteraction="REF_HttCffDefauConteFilte (Default Content Filter)" 
size="176" request="0xd99aaa00" url="https://10.1.10.2/" referer="" 
error="" authtime="0" dnstime="2" aptptime="579" cattime="317" 
avscantime="0" fullreqtime="2413" device="0" auth="0" ua="" exceptions="" 
category="9998" reputation="unverified" categoryname="Uncategorized" 
country="N/A"

Our core switch is the 172.17.17.2

10.1.10.2 is not a valid IP address on our network

What do you suppose the best way to try to track down the source of this is?

Thank you,

Tim