DIAGNOSIS: The TV's network adapter is likely getting stuck in a low-power or sleep state and failing to re-establish the connection. It's a known power management bug in the Tizen OS for this series.
FIX: Go to Settings > General > Network > Network Status. Run the diagnostic tool. Then, go into Expert Settings and manually set your IP settings to static instead of DHCP. You'll need to enter your router's gateway and DNS info (often just your router's IP address). This prevents the TV from constantly renegotiating its IP address, which is usually the point of failure.
IF THAT DIDN'T WORK: The 2.4GHz band is more stable for Smart TVs than 5GHz over distance. In your network settings, forget the 5GHz network and only connect to the 2.4GHz one. Also, disable any 'Quick Start+' or 'Instant On' features in Settings > General, as they can interfere with network standby.
HEADS UP: If you're using a VPN or custom DNS (like Cloudflare or Google) in the TV's settings, that's almost certainly the culprit. Switch back to your ISP's automatic DNS to see if the problem stops.