erc-disconnected-hook

erc-disconnected-hook is a variable defined in `erc.el'.
Its value is

(erc-unset-network-name erc-modified-channels-update)

Original value was

• This variable may be risky if used as a file-local variable.

Documentation:
Run this hook with arguments (NICK IP REASON) when disconnected.
This happens before automatic reconnection. Note, that
`erc-server-QUIT-functions' might not be run when we disconnect,
simply because we do not necessarily receive the QUIT event.

You can customize this variable.