Diagnosis
The TV's network software or hardware is having trouble maintaining a stable connection, often due to IP address conflicts or a weak WiFi signal.
How to Fix It
Start by giving your TV a reserved IP address on your home router. This is done in your router's settings, not the TV. Log into your router (usually via a web browser), find the list of connected devices, find your Toshiba TV, and assign it a 'DHCP Reservation' or 'Static IP'. This stops other devices from taking its IP and confusing the connection.
If That Didn't Work
The TV's WiFi antenna or card might be faulty. As a test, try connecting via an Ethernet cable directly to your router if possible. If the wired connection is stable, it confirms the WiFi hardware is the issue. You can also try a WiFi extender closer to the TV.
Heads Up
Avoid using the 'Network Test' in the TV settings too often. On some models, running that test repeatedly can actually corrupt the network configuration. Set it up once, and if it works, leave it alone.