Grosso problema,
prima delle varie modifiche e prove avevo questi settaggi:

TCP options string = 020405b4010303000101080a0000000000000000
01010402
MTU = 1500
MTU is fully optimized for broadband.
MSS = 1460
Maximum useful data in each packet = 1460, which equals MSS.

Default Receive Window (RWIN) = 8192
RWIN Scaling (RFC1323) = 0 bits
Unscaled Receive Window = 8192

For optimum performance, consider changing RWIN to a multiple of MSS.
Other values for RWIN that might work well with your current MTU/MSS:
513920 (MSS x 44 * scale factor of 8)
256960 (MSS x 44 * scale factor of 4)
128480 (MSS x 44 * scale factor of 2)
64240 (MSS x 44)
bandwidth * delay product:

Your RcvWindow limits you to: 327.68 kbps (40.96 KBytes/s) @ 200ms
Your RcvWindow limits you to: 131.072 kbps (16.384 KBytes/s) @ 500ms
Consider increasing your RWIN value to optimize TCP/IP for broadband.
MTU Discovery (RFC1191) = ON
Time to live left = 24 hops

TTL value is ok.
Timestamps (RFC1323) =
Timestamps (RFC1323) = ON
Note: Timestamps add 12 bytes to the TCP header of each packet, reducing the space available for useful data.

Selective Acknowledgements (RFC2018) = ON
IP type of service field (RFC1349) = 00000000

Ora dopo innumerevoli tentativi di settaggio di RWIN, purtroppo senza nessun miglioramento(da 17520 fino a 64240)e dopo varie telefonate con l'assistenza (Alice flat 256) mi ritrovo con i download sempre uguali media 28/30kb ma con ping altissimi su quasi tutti i server usuali dove "prima" giocavo con una media di 230/250 di ping ora non scende mai sotto i 300???
Come posso fare per tornar ai valori di prima?

Ora ho rienserito il Rwin di prima ma il problema rimane :
TCP options string = 020405b40103030001010402
MTU = 1500
MTU is fully optimized for broadband.
MSS = 1460
Maximum useful data in each packet = 1460, which equals MSS.

Default Receive Window (RWIN) = 8192
RWIN Scaling (RFC1323) = 0 bits
Unscaled Receive Window = 8192

For optimum performance, consider changing RWIN to a multiple of MSS.
Other values for RWIN that might work well with your current MTU/MSS:
513920 (MSS x 44 * scale factor of 8)
256960 (MSS x 44 * scale factor of 4)
128480 (MSS x 44 * scale factor of 2)
64240 (MSS x 44)
bandwidth * delay product:

Your RcvWindow limits you to: 327.68 kbps (40.96 KBytes/s) @ 200ms
Your RcvWindow limits you to: 131.072 kbps (16.384 KBytes/s) @ 500ms
Consider increasing your RWIN value to optimize TCP/IP for broadband.
MTU Discovery (RFC1191) = ON
Time to live left = 56 hops

TTL value is ok.
Timestamps (RFC1323) = OFF
Selective Acknowledgements (RFC2018) = ON
IP type of service field (RFC1349) = 00000000


Aiuto!!!!
Grazie