I’m having the same issue this morning. It won’t connect via the Samsung TV app, The Windows 10 app.
Windows 10 was brand new install of the tablo app.
I have completely removed the app from the TV .
I have reset my network (even though it appears to be fine)
I have verified that I can contact Tablo receiver via ping from various devices.
I’m connected via ethernet, and since at least one of my devices is connecting fine. I will assume it is working.
Any ideas?