USB, sound and Ethernet problems with Thunderbolt displays

This is an information about problems related to USB, sound an Ethernet with a Thunderbolt displays (TD) connceted to a MacBook Pro.

Context:

• MacBook Pro,
• Thunderbolt display
• Wifi and Ethernet connexion to the same network

Possible symptoms:

• keybord (connected by USB) to the TD stops responding,
• no sound and TD not visible in sound System Preferences,
• no Ethernet connection through TD,
• no battery charge by TD USB ports (iPad for example).

Soltions tried unsuccessfully:

• smc or pram resets,
• unplugging TD and/or MacBook Pro,
• rebooting,
• firmware and software updates,
• multiple phone calls to Apple support,
• TD mother board replacement,
• TD power board replacement.

Solution that worked (found thanks to a clue given by Will.G on another thread in this forum):

• deactivate Airport,
• disconnect and reconnect the thunderbolt cable.

It looks like TD sound and USB ports are linked to the network Ethernet connexion...

Hope this will help those facing similar problems.