I cant access some websites. I can visit a lot of web sites on the internet without a problem. But a few simply dont work. The strange thing is that they work for other people, or from other machines. Whats going on I touched on several possibilities for this in a previous article Why can I not access certain web sitesId certainly recommend that as a starting point. However, since that article was written, an additional reason for some web sites not being accessible has surfaced thats worth looking into in a little more detail. Its very obscure, but the good news is that it might also resolve some other problems, most commonly problems with instant messaging. C289&ssl=1' alt='Aol Internet Security Download Free Avira Premium' title='Aol Internet Security Download Free Avira Premium' />Download the free trial version below to get started. Doubleclick the downloaded file to install the software. Ftdi Usb To Db9 Serial Port Adapter Cable. I can visit a lot of web sites on the internet without a problem. But a few simply dont work. The strange thing is that they work for other people, or from other. TM9U' alt='Aol Internet Security Download Free Avira Premium' title='Aol Internet Security Download Free Avira Premium' />The issue is an obscure setting called MTU, which stands for Maximum Transmission Unit, in the network configuration. Ill describe it in a little more detail in a second, but first if youre having a problem, lets look at your current setting, and perhaps try tweaking it. MTU is buried in the registry, but rather than edit the registry directly, theres a small program you can download for free that will allow you to view and change the MTU settings Dr. TCP.  Download and run the latest version, and you should see something like this I know it looks a little intimidating, but dont worry. Were going to pay attention to only the two items in Adapter Settings. You can safely ignore the rest. First we need to make sure that the correct network connection or adapter is selected. Even if you have only one network connection, there are often several others. In Adapter Settings the field on the left is a dropdown list of all the network adapters on your system If the MTU setting is causing you problems accessing some web sites, its probably because its set too high. Make sure that the adapter that corresponds to your internet connection is selected. Normally thatll be the adapter that provides you your Local Area Connection as you can see in my case its an Intel PRO1. Once its been selected, the field on the right within Adapter Settings will show the MTU setting currently in use for that adapter. If the MTU setting is causing you problems accessing some web sites, its probably because its set too high. As you can see my default is 1. Unless youre on a dial up connection, larger numbers make for a somewhat faster network connection unless it doesnt work at all. Write down the MTU value you found to start with, and then try these valuesin order Do that by replacing the value in the MTU field again, making sure that the correct adapter is selected, and clicking Save, and then Exit. You will then need to reboot and test to see if the new value has corrected the problem. Important if the smaller values dont resolve your problem, then do remember to reset the MTU value to whatever it was when you started. So thats all been pretty much black magic and obscure numbers. What does it all mean When information is transferred across a network, its broken into chunks called packets. The Maximum Transmission Unit is related to the largest packet size that your computer will attempt to send. Each packet has overhead information that is not data, but rather information that says things like Im packet 1. IP address, heading for that IP address. Larger packets are more efficient in reliable networks, because since the overhead is fixed per packet, you spend a higher percentage of your time sending actual data and less on overhead. Free Download Games For Pocket Pc Cab there. A 1. 50. 0 byte packet with 1. There are also other factors including latency, packet delays and the like that make larger packets more efficient. Unless the network is unreliable. Thats why youll often see smaller maximum sizes on dial up networks. If a packet gets lost, which does happen from time to time, a smaller packet is more efficient to re send than a larger one. Oracle 11G Oe Schema. You can see that its not just magic, but also fairly complex. But it does boil down to the characteristics of the network between you and the site or service that youre attempting to use. The standard values for MTU are typically 1. As you saw, this is the value my machine uses, connected to my LAN, which in turn is connected to a router and a DSL connection to the internet. PPPo. E require this value, and if youre having a problem actually related to MTU, theres a high likelihood that this value will in fact work for you. If youre connected to the internet via equipment that requires a smaller value, or, while rare, the remote site youre trying to access is connected via equipment that requires a smaller value, youll simply be unable to connect. Adjusting your MTU value is one thing to try. Update another common reason for not being able to visit certain websites is detailed here Why did my home network stop working Update 2 another very common solution is to clear your browser cache.