Problema con el servidor al subir documentos

Hola a todos,

Estos realizando una web donde se suben docuementos. Cuando éstos pesan
menos de 1 mega funciona correctamente, pero cuando es igual o mayor a un
mega me sale el siguiente error:


Most likely causes:
You are not connected to the Internet.
The website is encountering problems.
There might be a typing error in the address.

What you can try:
Check your Internet connection. Try visiting another website to make
sure you are connected.

Retype the address.

More Information:
This problem can be caused by a variety of issues, including:
• Internet connectivity has been lost.
• The website is temporarily unavailable.
• The Domain Name Server (DNS) is not reachable.
• The Domain Name Server (DNS) does not have a listing for the website's
domain.
• If this is an HTTPS (secure) address, click tools, click Internet
Options,
click Advanced, and check to be sure the SSL and TLS protocols are enabled
under the security section.


Alguien me puede ayudar con este problema, no encuentro la solución.

Muchas gracias y un saludo,