Bizarre download speed throttling only present in XP

[sparty411]

I'm encountering a weird problem where my my internet connection speed seems to be throttled down to 20mb/s only when I'm using Windows XP. This occurs when I'm using my Realtek 8811CU WiFi adapter, as well as the onboard Realtek LAN on the mobo. Under Windows 11 this problem is not present, as I'll achieve DL speeds up to 300mb/s, and it also occurs when I'm using a completely different motherboard, and different installation media. I've fiddled with the qos packet scheduler in the group policy editor, and that made no difference either. Does anyone have any ideas?

Edited July 27, 2024 by sparty411

[Dixel]

Could be the XP driver limit.

[AstroSkipper]

21 hours ago, sparty411 said:

I'm encountering a weird problem where my my internet connection speed seems to be throttled down to 20mb/s only when I'm using Windows XP...
Does anyone have any ideas?

Just an idea. Have you already patched and removed the limit on TCP connection attempts in the tcpip.sys file in your Windows XP installation?  This can be done, for example, with the tool xp-AntiSpy, or manually following the instructions here: https://www.speedguide.net/articles/windows-xp-sp2-tcpipsys-connection-limit-patch-1497/p-2/ There, you can find a further tool for patching called Event ID 4226 Patcher: http://www.lvllord.de/?lang=en&url=tools Long time ago, I did it with xp-AntiSpy which also creates a backup of the original file. 

Edited July 28, 2024 by AstroSkipper
Update of content

[AstroSkipper]

On 7/28/2024 at 10:32 AM, AstroSkipper said:

On 7/28/2024 at 1:54 AM, sparty411 said:

I'm encountering a weird problem where my my internet connection speed seems to be throttled down to 20mb/s only when I'm using Windows XP...
Does anyone have any ideas?

Just an idea. Have you already patched and removed the limit on TCP connection attempts in the tcpip.sys file in your Windows XP installation? 

And don't forget to adjust your MTU and RWIN values as Windows XP does not do it automatically! This can be easily done, for example, with the tool SpeedGuide.net TCP Optimizer, currently in the version 4.1.1.  The correct MTU value mainly depends on your internet provider and can even be determined with the SG TCP Optimizer tool in the corresponding tab. A suitable RWIN value can also be manually calculated and set in the registry, of course. All values should be then tested to find the optimal ones. In any case, be aware that such fast connection speeds as you are using today didn't exist when Windows XP was developed and still maintained.   TBH, I don't know whether Windows XP with its very old network drivers is at all able to handle such high speed you mentioned above.  The old Internet tariff I  booked years ago has a speed of 25 Mbit/s only, which I can achieve in full on my Windows XP computer, but only with optimal settings mentioned above. However, my old processor wouldn't be able to cope with any more, either.  And regarding the QoS Packet Scheduler, I deactivated it from the very first on my standalone Windows XP desktop computer long, long time ago. 

Edited July 29, 2024 by AstroSkipper
Update of content

[AstroSkipper]

@sparty411 Are you sure about your specifications regarding your internet speed?  The unit mb/s does not actually exist.  You wrote 300 mb/s. Did you really mean 300 MB/s or perhaps 300 Mbit/s?  If you really had a speed of 300 MB/s, then that would be a line with 2400 Mbit/s, which I have never heard of existing for a normal citizen.  At least here in Germany.  I assume you rather meant 300 Mbit/s (Mbps in English, and very rarely can also found the unit Mb/s). 

Edited July 28, 2024 by AstroSkipper
Update of content

[user57]

https://www.speedguide.net/faq/what-is-the-difference-between-kilobits-and-kilobytes-166