I checked on the Netgear web site for this info you may get a better answer on the network forum
1. You have problems connecting to your ISP or other Internet service, and their technical support (or NETGEAR's) recommends changing MTU. For example, these services may require an MTU change:
* Yahoo email
* AOL's DSL service
2. You use VPN, and have severe performance problems.
3. You used a program to "optimize" MTU for performance reasons, and now you have connectivity or performance problems.
* An easy solution to most problems is to change MTU to 1400.
* If you are willing to experiment, gradually reduce MTU as described in "Details of MTU", below.
How to Change a Computer's MTU Size
Note: If you change MTU on one computer, it is likely you will want to change it on your other computers, switches, and routers, as well. Instructions for changing MTU on other NETGEAR devices is found in the Reference Manuals.
The third party Dr. TCP software can be used to change the MTU setting.
1. Download it from this link, choosing the zip file or the exe file at the top of the page.
2. Run the utility.
3. In the Adapter Settings pull down, select the Ethernet driver and adapter used to connect with the network.
4. In the MTU box, type the MTU size you are trying.
5. Click in any other box, without changing the data there.
6. Click Save.
7. Click Exit.
8. Restart the computer.
free tune up http://www.pcpitstop.com