So now I'm really confused. Line 89 is get_internal_url, which pulls the internal URL config from the database, which is
http://192.168.1.12/nagiosxi/
But that's not the URL that's being hit as shown in the /var/log/httpd/error_log file. I'll see if I can highlight the stuff that's of interest, below. Note that the correct external URL, complete with port, is specified the first time when the actual error comes in (DOMDocument::loadHTML(): Unexpected end tag : p in Entity, line: 8208 in /usr/local/nagiosxi/html/includes/components/objconfig/objconfig.inc.php on line 198). But from then on it only shows that it's trying to connect to the external URL without the port.
So if it's using internal URL on line 89 of the PHP you mentioned, then it's somehow getting external URL when it makes the request.
[Sun May 06 14:10:00 2018] [error] [client 173.239.221.130] PHP Warning: DOMDocument::loadHTML(): Unexpected end tag : p in Entity, line: 8208 in /usr/local/nagiosxi/html/includes/components/objconfig/objconfig.inc.php on line 198, referer: http://
EXTERNAL.EVERWATCH.GLOBAL:8675/nagiosxi/includes/components/xicore/status.php?show=services&servicegroup=SVGP+Peers&servicestatustypes=16
--2018-05-07 16:31:32-- http://
EXTERNAL.EVERWATCH.GLOBAL/nagiosxi//reports/execsummary.php?reportperiod=last24hours&startdate=&enddate=&host=&service=&hostgroup=&servicegroup=&advanced=0&assumeinitialstates=yes&assumestateretention=yes&assumestatesduringdowntime=yes&includesoftstates=no&assumedhoststate=3&assumedservicestate=6&timeperiod=&username=nagiosadmin&ticket=jdr6imlt&locale=en_US&mode=pdf
Resolving
EXTERNAL.EVERWATCH.GLOBAL... 72.45.161.114
Connecting to
EXTERNAL.EVERWATCH.GLOBAL|72.45.161.114|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 350 [text/html]
Saving to: "/usr/local/nagiosxi/tmp/scheduledreport-nagiosadmin-eB7okT-execsummary.pdf"
0K 100% 31.0M=0s
2018-05-07 16:31:32 (31.0 MB/s) - "/usr/local/nagiosxi/tmp/scheduledreport-nagiosadmin-eB7okT-execsummary.pdf" saved [350/350]