I've instructed artio sef to show a custom 404 page but Joomla is displaying the standard red page. How would I get support to help fix this?

Hi,
Try disabling the "Parse Joomla SEO links" option in JoomSEF's Configuration on the Advanced tab.

I'm afraid that had no effect. Any other ideas?

What versions of Joomla and JoomSEF do you use? Does this happen for any non-existent URL? Could you post some example of URL that displays the default Joomla's 404 page? Is there an article named "404" created in Joomla? It should be created automatically by JoomSEF.

FYI Changing the setting created a whole site of 404's.

What versions of Joomla and JoomSEF do you use?
1.5.26
3.9.8 according to the change log

Does this happen for any non-existent URL?
I don't know how to test that.

Could you post some example of URL that displays the default Joomla's 404 page?
www.planetherbs.com/x
www.planetherbs.com/index.php?option=com_fireboard


Is there an article named "404" created in Joomla?It should be created automatically by JoomSEF.
yes

What do you mean by whole site of 404's? All SEF URLs displayed on your website show 404 page?

The www.planetherbs.com/x URL seems to display custom 404 page.
Because of the way Joomla works, JoomSEF currently can't display 404 page for URLs like www.planetherbs.com/index.php?option=com_fireboard - from JoomSEF's point of view it's a legitimate URL. JoomSEF can display custom 404 page only for SEF URLs it doesn't find in its database.