CMS Made Simple "URL not found" admin login error

Question

I've implemented CMSMS and created a website on it http://www.razvoj-karijere-vukovar.com/, index.php is being redirected on under_construction.html thru .htaccess.

Login on admin panel thru http://www.razvoj-karijere-vukovar.com/admin is working from my office, from my smartphone, from my home, from any of the browsers and internet providers I used, BUT once I try to login from my clients building on any of the PCs I get this error:

Not Found 
The requested URL was not found on this server.

Don't know why, have no idea how to go about it :/

What really got me baffled is that I can successfully log in into CMSMS admin panels on other sites from my client PCs.

Any suggestions at all? Maybe ideas how to debug it? Thanks!

Answer 1

Step 1

Open the list content page in the Admin: Content >> Pages

Create a new page, by clicking on "Add new content"

Step 2

Change the Content Type to Error page

Change the Error Type to, for example, "Page not found (404)"

Enter the title of the error page, for example "Error 404" and add some related content.

Step 3

Enter your own content text and/or images.

Save your page by hitting "Submit" and the your customized error page is ready.