The information about connection type and appropriate MTU restrictions, specified here, is used to choose the proper optimization scheme. Tips displayed in the bottom of the page can assist you to make a right choice.

If you don’t know exactly which connection type you have, it is recommended to select the first option (Digital modem or Ethernet with MTU <= 1500).

Actually, there is a reason to choose the option with the bigger MTU. Let’s consider an example to illustrate that. If you choose MTU <= 1492 option, but the network media supports MTU = 1500, you simply lose your network performance, because usually the bigger MTU gives the higher speed.

Thus, it is recommended to choose MTU <= 1492 only in case if you know for sure, that network media does not support MTU > 1492 (it is true for PPPoE). Otherwise, choose the option with the highest MTU (<= 1500).

What if you choose incorrect option here?

If you choose the first option with the highest MTU, but the network media supports only lower MTU, after optimization and restart the biggest supported MTU will be used. If it will be lower than MTU set during optimization, SySpeed will ask to re-optimize your system to set TCP/IP settings in accordance with that lower MTU value, and next time SySpeed will prompt you that your network media supports some restricted MTU value.