My application manages an online ordering system. Testing is done on a local server using localhost domain name. Fedora 35 with Apache server. Application is PHP. The application creates a list of orders using a MySQL database. The list is presented and an order can be accessed via a link (which uses localhost domain in the URL). This step works fine, the order is displayed for the user. A link on that display allows the user to enter a small message for the order, that link uses localhost domain in the URL. That link works fine, the screen where the user can enter the small message is displayed. When the user inputs the message and presses the submit button of the form (the URL for the form is, once again, using localhost in the URL), the application hangs for a minute and a 504 Gateway Timeout error message is displayed. I have examined the simple html code thoroughly and find no obvious errors. I have tried many different kinds of URL specifications in the form with no difference in result. I have replaced the 'submit' in the form with a Javascript call to submit the form, with no change in result. I have run the application with and without internet connectivity with the same results. I am trying to understand why several steps preceding this failure, all using the same URL format and all accessing localhost are successful, but this one fails. I can provide the html if needed. Help badly needed. Thanks in advance. Regards, Bill Lee