1. Check your router to make sure that it supports IMAP/POP3.
2. Check if the mailbox service is running.
3. Temporarily disable any third-party anti-virus software installed on your computer, firewall and other security measures if applicable.
4. Check the DNS settings of the computer being used to connect to the server.
5. Test the connection using an alternate email client if available.
6. Increase the server timeout setting on the email client being used.
7. Contact your router/ISP for further clarification and assistance.