After I modified the ip address through the web interface, I forgot this address.
I can't enter the board using the serial port. I don't know what I need to do.
The best way to do this is to wipe the EEPROM using the bootloader. The TSN Quickstart guide shows a user how to use the bootloader for updating software. Basically once you are in the bootloader instead of loading anything, simply type "wipe". This will restore the default settings.