The "Only secured content is displayed" pop-up message typically indicates that some of the resources on the website you are trying to access are being served over an insecure connection (HTTP). Here are a few things you can try to fix the issue:

 

1. Check the website's SSL certificate: Verify that the website has a valid SSL certificate and that it is installed correctly. You can do this by clicking on the padlock icon in the address bar of your browser and checking the certificate details, or you can use a tool like SSL Labs to check the certificate.
2. Check the website's links and resources: Make sure that all links, images, and other resources on the website are being served over a secure (HTTPS) connection. If you find any resources that are being served over an insecure connection, try contacting the website administrator to have them fix the issue.
3. Update your browser: Make sure that you are using the latest version of your browser, as older browsers may not be able to access websites using the latest security protocols.
4. Clear browser's cache and cookies: Clearing your browser's cache and cookies may fix issues related to SSL certificates.
5. Disable VPN or proxy: If you are using a VPN or proxy, try disabling it and accessing the website again.
6. Check your firewall settings: Make sure that your firewall or antivirus program is not blocking the connection.
7. Check with your IT administrator: If you are facing this issue on a work/corporate network, you might want to check with your IT administrator as there might be some internal policies or network configurations that might be causing the issue.
8. Contact the website administrator: If you are still unable to access the website after trying the above steps, you may want to contact the website administrator and inform them of the issue. They may be able to help you resolve the issue.

It's important to note that mixed-content warnings can also be raised if a website includes external resources such as scripts, images, fonts, etc, which are not served over HTTPS.