I can't surf the Web from the PC that is connected with the Multiconnect.

You can not surf the Web if the PC is connected to the MTS2SA. The MTS2SA was not designed for surfing the Internet.

The MTS2SA is designed for dumb legacy serial equipment that does not have an IP stack. The MTS2SA only has limited built-in IP applications such as SMTP, POP3 and FTP clients that the external serial device can use.