I've read your post several times and I'm having trouble understanding your configuration. A nswers to a few questions may help clear things up.
Where is the Linksys WUSB600N plugged in to?
Do you have wifi on the Actiontec turned on or off?
What type devices are you measuring that upload speed with? PC/Mac? Mobile phone or tablet? Can you try the speed test with the TV on using a PC or Mac connected directly to the Actiontec via Ethernet cable?
And when you turn on the TV, are you just watching a standard TV station channel, channel 2, 502, etc?, or are you watching one of the streaming services like Netflix, Amazon, Hulu, etc?