Windows – Server Manager For telnet

Have you tried disabling the auto-tuning diagnostic in Windows 7?

netsh int tcp set global autotuninglevel=disabled

Microsoft Support KB article:

When the receive window autotuning feature is enabled, older routers, older firewalls, and older operating systems that are incompatible with the receive window autotuning feature may sometimes cause slow data transfer or a loss of connectivity.

The default auto-tuning level is "normal", and the possible settings for the above command are:

• disabled: uses a fixed value for the tcp receive window. Limits it to 64KB (limited at 65535).
• highlyrestricted: allows the receive window to grow beyond its default value, very conservatively
• restricted: somewhat restricted growth of the tcp receive window beyond its default value
• normal: default value, allows the receive window to grow to accommodate most conditions
• experimental: allows the receive window to grow to accommodate extreme scenarios (not recommended, it can degrade performance in common scenarios, only intended for research purposes. It enables RWIN values of over 16 MB)

Well, found the solution. The service that manage Server Manager features installation is "Windows Modules Installer". It is not possible to manually restart it. To do so, go and kill task named "TrustedInstaller" (close Server Manager before). Service will stop. Start it. Open Server Manager and feature installation should be gone.