Straight from SolarWinds tips and tricks:
Changing the internal communication port used by TFTP Server SolarWinds uses an internal communication port to communicate between the windows service and the various applications. To override the default port of 8099:
Shut down all Toolset applications including the TFTP Server tray application and the TFTP service.
Create a file named TFTPCommPort.conf with the desired port number as the only content of the file.
Place the file in the common application data directory (older Windows version use C:\Documents and Settings\All Users\Application Data\SolarWinds, newer Windows versions use C:\ProgramData\SolarWinds).