ISDN tweak guide (Windows 98 & ME)

Setting MTU/TTL/RWIN (Continued)

Now change the MTU & TTL (Maximum segment size, or MSS is not settable in Windows 9x/Me, it is automatically determined by your MTU so don't waste time needlessly setting it). Take the following steps. NOTE If you only have a single modem in your PC, i.e. No Ethernet card installed in your machine also, then you can skip to Step 5 as there should only be one key(s) available, 0000.

1.       You have to find the details of your Dial-Up Adapter. Find the key [HKEY_LOCAL_MACHINE\Enum\Root\Net\000x] & within there will be one or more sub-keys such as 0000, 0001, etc.

2.       Open each key & find the one that contains the value of DeviceDesc equal to Dial-Up Adapter.

3.       Within that key there will also be another sub-key named Bindings. Open the Bindings sub-key & you will find a string named MSTCP\000x. Take note of the four-digit number after MSTCP\ (in this case 0000) & use it in the next step.

4.       Now go to the key [HKEY_LOCAL_MACHINE\Enum\Network\MSTCP\000x] & expand the sub-key with the same four-digit number as from the previous step.

5.       In this key you will find a value called Driver & there will be an entry entitled NetTrans\000x. Take note of the four-digit number & use it in the next step.

6.       Now open  [HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\ Class\NetTrans\000x]. Expand the key with the value equal to the four-digit number from the previous step.

7.       Within this key create a new string value named MaxMTU & set it to your MTU (e.g. 1500), which you discovered in the MTU, TTL & DefaultRcvWindow section.

8.       Next go into [HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\ Class\Net\
, in here you will find entries for Automatic, Large, Medium & Small. Right click in the right hand side of the box & make a New String Value equal to your MTU e.g.
1500, right click on this new entry & select modify, type in Automatic then click Ok. Delete all the other values there, e.g. Large - Small & the other Automatic (if any).

9.       Now open [HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\ Class\Net\000x]. Right click on IPMTU & select modify, change this value to whatever your current MTU you (e.g. 1500).

10.   Go into [HKEY_LOCAL_MACHINE\System\CurrentControlSet\
, change the default value to your current MTU (e.g. 1500).

11.   Exit the registry & restart your computer for the changes to take effect.

You can change the settings as necessary.


This tweak can reduce the amount of Timeouts you may experience when online.

1.       Open Regedit (Click on Start, Run, type in regedit & hit Enter), go to [HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Class\Net\000x]. Where x represents the folder with the Slownet entry.

2.       In the right hand pane, right click on Slownet & select Modify, change the value from 01 to 00.


Hopefully now your connections will be quicker, downloads faster, ping times lower etc. If you have any questions or comments feel free to email us.


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