Thank you for confirming,
since it happened on the old one too, that is an indication that this is actually a hardware fault in the tv.
The internal wifi adapters in these tvs are very small and underpowered, and typically die after a few years from overheating inside the tv.
Using a wired ethernet cable would be the alternative, as this issue isn't practical to repair.
If you can't do wired direct to the router, the next best option would be to approximate that by using the wired lan port in conjunction with a
powerline ethernet adapter:http://amzn.to/28SDK86 or wifi bridge: http://amzn.to/28PrUHk
Even that may not be worth the investment however, while minimal if you were going to spend it you'd be better off to spend another $10 and get a on a roku or fire tv. Being an older model tv that is no longer supported, many of the apps on it don't even work anymore (amazon, youtube) and those that do are slow and glitchy, and will continue being dropped over time. So for just a bit more you can connect a much more capable external streaming device, or just stick with your bluray too.
My apologies for the news.
If you have any other questions, just let me know. Otherwise, please take a moment to rate my service as this is the only way I am credited for my time. Hopefully I have earned 5 Stars but if not please let me know what I can do to ensure you are satisfied. I also invite you to contact me directly with any future support needs at http://bit.ly/1QwLxGh and ask for Nathan.
Thank you, ***** ***** a nice day,