Has it worked before?
How have you proved that the TV is the problem and that the problem is not in the sub woofer?
Try using a WiFi scanner program in a laptop or a PC with WiFi capability to see if the TV is sending the signal. If you cannot detect a signal then the problem is in the TV, (Double check that the Wireless Speaker setting in the Audio menu section of the TV is set to ON). If there is a signal the problem may be in the sub woofer. The scanner program will also tell you what channel the WiFi is using (if it is working) and whether or not there are other WiFi networks nearby which may be using the same channel and causing interference to your signal. Reading the user guide for your TV indicates that if there is interference from another network using the same channel, you have to change the channel in the other network, if you can, as the TV WiFi channel cannot be changed.
Here is a link to just one free WiFi scanner program, (there are others, just search online). Download, install and run it to see if the TV is sending a WiFi signal on the 5.8GHZ band. That way you will know where to start looking for your problem.
If the problem is in the TV here is a link to the TV's service manual.
To download the manual, when the sentence below the Document preview box changes from This file is downloadable free of charge:..processing.. to This file is downloadable free of charge: Get Manual, click on the Get Manual as this is the download link. Be patient it takes a little while for the file to be found.
If you scroll to p.9-8 there is a flow chart on how to troubleshoot the Sub Woofer not working problem. It mentions a TX/RX module (which I think is mounted on the Audio board) but unfortunately it does not give a part number for the module. It should however be printed on the module itself so that perhaps you can get it from there.. There is also a mention of a "Module Transmitter" Item #40 in the parts inventory at the end of the document, which may be worth looking at as it seems to be connected via a cable into the mainboard.
Hopefully this is of some help.