Can I detach the primary (eth0) network interface when the instance is running or stopped?
A.
Yes, You can.
B.
No. You cannot
C.
Depends on the state of the interface at the time
when the instance is running or stopped?
Can I detach the primary (eth0) network interface when the instance is running or stopped?
No. You cannot
Instance must be stopped.
Even instance stopped you can’t detach the primary (eth0) network interface