Thanks again for all your assistance.
Lots of information requested, I will do the best I can.
1. Status, below is the captured image, and yes it is a network timeout:
2. The Headers data was over 1 page in size so captured in two separate screen grabs:
WYSIWYG Header 1:
WYSIWYG Header 2:
3. Changed to https from http for site URL in admin/general; then retested image upload.
Unfortunately no difference.
4. I presume you mean try the upload again after changing from http to https.
I did and no difference.
5. The image is jus a screen capture from GIMP, and I uploaded it to my 1.8.1 Q2A version instance at home no issue.
6. No reason, just using default out of the box Q2A install.
7. Yes, i.e.:
$ php --info | grep errordisplay_errors => STDERR => STDERR
display_startup_errors => On => On
error_append_string => no value => no value
error_log => syslog => syslog
error_prepend_string => no value => no value
error_reporting => 32767 => 32767
html_errors => Off => Off
ignore_repeated_errors => Off => Off
log_errors => On => On
log_errors_max_len => 0 => 0
track_errors => Off => Off
xmlrpc_error_number => 0 => 0
xmlrpc_errors => Off => Off
intl.error_level => 0 => 0
opcache.error_log => no value => no value
8a. I am not familiar with GD extension, so my guess is NO.
8c $ php -v
PHP 7.3.31-1~deb10u1 (cli) (built: Oct 24 2021 15:18:08) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.3.31, Copyright (c) 1998-2018 Zend Technologies
with Zend OPcache v7.3.31-1~deb10u1, Copyright (c) 1999-2018, by Zend Technologies
9. Yes, uploaded my avatar (jpeg) as default image, no issues.
On the 'Disable cache', I presume you want me to select that before attempting any future debugging.