Help for TCP Window configuration

[nandone]

Good morning

I have a 1 Gb fiber connection, win 7 and Chrome 109 and I set TCP Optimizer with these data:

Chose settings: Optimal
Connection speed = 100+Mbps
MTU = 1500
Autotuning TCP = Normal

I checked with SG TCP/IP Analyzer, with these results:
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« SpeedGuide.net TCP Analyzer Results »
Tested on: 2023.01.20 11:59
IP address: 95.251.xxx.xxx
Client OS/browser: Windows 7 (Chrome 109.0.0.0)

TCP options string: 020405b401010402
MSS: 1460
MTU: 1500
TCP Window: 64240 (multiple of MSS)
RWIN Scaling: 0 bits
Unscaled RWIN : 64240
Recommended RWINs: 64240, 128480, 256960, 513920, 1027840
BDP limit (200ms): 2570 kbps (257 Kilobytes/s)
BDP limit (500ms): 1028 kbps (103 Kilobytes/s)
MTU Discovery: ON
TTL: 119
Timestamps: OFF
SACKs: ON
IP ToS: 00000000 (0)
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I noticed the TCP Window value at 64240, when it should be with BPD calculator with 1Gbit fiber and 5ms average latency, at least 625000.

I ask for your help to understand what this value depends on and how to raise it.
NB: Before the fiber i had a 7 Mbps ADSL.

Thanks to whoever can help me.

[Philip]

Newer Windows variants only show the "current" RWIN value, rather than the maximum, and then the autotuning algorithm scales it up as necessary depending on line conditions. I wouldn't worry about the Analyzer showing a smaller value.

[nandone]

Thanks Philip. For information, I set TCP autotuning to Experimental, but I encountered some problems: sometimes the download speed drops considerably and then rises again and also the Ookla app from PC doesn't work.

Thanks again for the reply.