You really need to explain more. This limited info wil not get you anywhere.
Use Google translate if your English is limited.
Hello! Really need help ...
The essence of the matter: buy dir-655. On 3 computers the NIC DWA-525, computers can see each other, small files are copied, the internet works fine, but if you start to copy large files> 50 MB, copying is interrupted after a minute, and happens at once and wrote "The specified network name is more not available. " What kind of nonsense is this??
What information from me so you can help me?