On a new N5300, both Wi-Fi and wired Ethernet connect successfully on first attempt, even switching back and forth, and streaming has no issues with either connection, but ...
For the wired connection only, the router doesn't see the TV as an attached device. To use it wired for more stability, I lose the router management of that networked device.
Resetting the network didn't solve issue. Cables and router ports are good and attach other networked devices (other TVs, PC, etc), just not this TV. Software is up to date.