I'm simply checking to make sure you have the latest version, though even this one is extremely out of date (2012).
The one remaining thing you could try here is routing an ethernet connection from the tv directly to your modem (bypassing the router and any other switches/devices) to test that way.
If that doesn't work, which honestly I do not expect it will, it is a compatibility issue at this point. All support for this model tv was discontinued long ago, and as they continue to update the panasonic proxy servers that all content is routed through, the older model tvs simply stop working for their smart apps. Most apps for this set have been completely dropped at this point already, for example youtube and amazon will not work on it at all, even if you do get the connection up and running, you may get netflix at best.
Ultimately your best option here, short of replacing the tv, is to forego the internal apps and connect an external streaming device instead such as a roku or fire tv and get all the same functions and many more, with better performance and lower cost and much better long term support.
My apologies for the news,