The workarounds detailed below apply especially to owners of 28,800 baud (or faster)
analog modems, to enable the fastest Internet connection supported by these modems,
connecting through the TCP/IP protocol, and using Dial-Up-Networking in Windows 95.
Since Windows 98 comes pre-optimised.

NOTE: MaxMTU + MaxMSS [Win95], IPMTU [Win98], DefaultRcvWindow, DefaultTTL and
cachesize are NOT present in your Registry if you have never used a "MTU tweaker" like
EasyMTU, MTUSpeed, TweakDUN, etc, or added them yourself using a Registry editor like


* Tweak "MaxMTU" + "MaxMSS":

There are two ways of doing this, but NOT BEFORE BACKING UP YOUR REGISTRY FILES:

TCP/IP NetTrans registry keys, you MUST customize YOURS from the below stated values to get similar results):











"MaXMTU" = Maximum Transmission Unit, or MTU (packet size in bytes).

Valid values: MTU = MSS + 40.

Respectively: 256, 576, 1006, 1500 (other values are valid as well,depending on the MTU
used by different ISPs).

Default: 1500.

Recommended: 576.

Data type: string:


"MaxMSS" = Maximum Segment Size, or MSS (segment size in bytes).

Valid values: MSS = MTU - 40.

Respectively: 216, 536, 966, 1460 (other values are valid as well, depending on the MSS used by different ISPs).

Default: 1460.

Recommended: 536.

Data type: string:


To determine EXACTLY which NetTrans keys you need to alter (and NO others), bear in mind that you MUST have this entry:


under EACH of your NetTrans keys you want to modify! Change/add the MaxMTU string ONLY under your NetTrans keys that have "TCP/IP" on the DriverDesc" line! You may have more than one  "000n"/"00nn" NetTrans keys ("n" and "nn" are actual numbers, ranging anywhere from 0 up to 50, depending on your system's Network/Dial-Up settings).

Here there are two possibilities:

A. If you already have a "MaxMTU" entry: double-click on the right hand pane

"MaxMTU" string, and type in 576. Click OK.

B. If you don't have a "MaxMTU" entry: you can add it manually, by double-clicking on EACH of your left hand pane TCP/IP NetTrans 000n/00nn keys and then selecting New -> String value. Name the new string MaxMTU. Double-click on it and give it a value of 576.

Repeat the steps above for ALL your TCP/IP NetTrans keys, to include the recommended values for both MaxMTU and MaxMSS. Restart Windows 95 when done so all changes can take effect.

NOTE: Some ISPs use a default packet size (MaxMTU) value of 1500, so it's a trial-and-error game. To make sure your Win95 Registry TCP/IP settings match the ones used by your Internet provider,  you may need to contact your ISP's support line or e-mail service, and ask them the exact values used for MaxMTU.

Then modify your Registry settings accordingly, to obtain maximum performance.


You might also see modem speed improvements over the Internet by upgrading to these Microsoft free communications updates/patches: A. Windows 95 + OSR2 users:
install the NEW PPP/PPTP/TCP/IP/ISDN Dial-Up Networking (DUN) Upgrade/Security
Patch v1.3 [2.24 MB]:


Windows Sockets 32bit (updated WINSOCK.DLL + WSOCK32.DLL) Upgrade 2.0:

MS WINSOCK Update 2.0 direct download [963 KB]:

B. Windows 98 users: install the NEW Dial-Up Networking Security Patch v4.0

[319 KB]:


1. I recommend using the new versions of these fine programs, the only ones that (so far)
apply ALL the Win98/95/MTU recommended tweaks described here:

- Rob Vonk's new EasyMTU v3.0, the first, the best and the only freeware
MTU/MSS/TTL/RWIN/COMBoostTime/cachesize/etc tweaking program [357 KB]: (RECOMMENDED)

EasyMTU v3.0 now includes FindMTU [a PING tool] to determine EXACTLY the MTU value used by
your ISP/Online Service

- Joseph Burke's new TweakDUN v2.22 [440 KB, shareware]:

- InfiniSource MaxMTU Fix home:

2. For extensive details/specs on analog/digital modems, Win98/95 communications, TCP/IP,  DUN and more MTU/TTL/RWIN/etc tweaking programs, check out these reference links:

3. READ this Microsoft TCP/IP Knowledge Base Article: "Windows 95 TCP/IP Registry Entries":

Here are the Registry keys that have to be modified to improve my modem Internet access speed:



























"DefaultRcvWindow" = Receive Window (machine's network fill buffer in bytes).

Valid values: (MTU - 40) x n or MSS x n, where n = 2, 4, 6, 8, 16.

Respectively: 1072, 2144, 3216, 4288, etc.

Default: 8192.

Recommended: 3216.

Data type:

- string (Win95):


- DWORD (Win98):


"DefaultTTL" = Time To Live (going over Net hops until destination is reached

in milliseconds).

Valid values: 32, 64, 128.

Default: 32.

Recommended: 128.

Data type: string (Win98 and 95):



MaxMTU + MaxMSS [Win95], IPMTU [Win98], DefaultRcvWindow, DefaultTTL and cachesize are NOT present in your Registry if you have never used a "MTU tweaker" like EasyMTU, MTUSpeed, TweakDUN, etc, or added them yourself using a Registry editor like Regedit. You can do this by modifying registry:

* Tweak "DefaultRcvWindow":

Start Regedit (found in your Windows folder) and go to:


In the right hand pane, look for (or create it if it's not present) this string:


The number you should have is 3216 (Win98/95 default value is 8192). The principle behind this setting is to calculate the optimal value for the DefaultRcvWindow string with this formula:

DefaultRcvWindow = (MTU - 40) x n = MSS x n

Where "n" is anything between 2 and 8 (fiddle with it and find out the best value for your machine, depending on your modem speed and your custom ISP settings). I used MTU = 576 in this example:

DefaultRcvWindow = (576 - 40) x 6 = 3216 respectively:

DefaultRcvWindow = 536 x 6 = 3216

Right-click on the above string, click Modify, and change the number to read 3216, which will default to the recommended calculated value. Exit Regedit and restart Windows when done.

If you find out (after connecting to your ISP with your modem, using the TCP/IP protocol, and then accessing some graphics intensive web sites, and downloading a few large files from the Internet) that a DefaultRcvWindow value of 2144 or 4288 works better on your system, please modify your

Registry DefaultRcvWindow key accordingly.

* Tweak "DefaultTTL":

Run Regedit and look under:


for the string below:


Create the "DefaultTTL" string if it's not already present, and assign it the value of "128" (Win98/95 default is 32). Experiment with your Internet hookup and lower the "DefaultTTL" value to 64 if you get better results. Do NOT type the quotes! Exit the Registry Editor and restart Windows.

Admin,Cyber Shaft.


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