[Goose]

I have not heard of an S-400 or S-400 component being taken out with FPV drones. ATACMS and GMLRS mostly. And one off claims of Neptune and long range fixed wing drone, though no video or other confirmatory evidence of those strikes. 

S-400 would usually be deployed too deep in the rear for FPV drones, unless perhaps some special forces team deployed with them behind enemy lines.

The only reference I found was this: https://www.bbc.com/news/world-europe-66805897. 

used drones to take out radar equipment, then cruise missiles to hit air defence missile launchers

The "radar equipment" may have been parts of a Tor or a Pantsir that was forward deployed to shoot down cruise missiles and/or aircraft that would launch such missiles. It is correct that normally an S-400 would be placed pretty far back. That said, Russia often gets sloppy. They may have got too close. The S-400 radar itself may have been the target of the drones.

There is some known bogus computer game videos out there showing drones destroying an S-400. That muddies the water a lot.

[Goose]

I have not heard of an S-400 or S-400 component being taken out with FPV drones. ATACMS and GMLRS mostly. And one off claims of Neptune and long range fixed wing drone, though no video or other confirmatory evidence of those strikes. 

S-400 would usually be deployed too deep in the rear for FPV drones, unless perhaps some special forces team deployed with them behind enemy lines.

The only reference I found was this: https://www.bbc.com/news/world-europe-66805897. 

used drones to take out radar equipment, then cruise missiles to hit air defence missile launchers

The "radar equipment" may have been parts of a Tor or a Pantsir that was forward deployed to shoot down cruise missiles and/or aircraft that would launch such missiles. It is correct that normally an S-400 would be placed pretty far back. That said, Russia often gets sloppy. They may have got too close. The S-400 radar itself may have been the target of the drones.

There is some known bogus computer game videos out there showing drones destroying an S-400. That muddies the water a lot.