First of all, TWebUpdate has a function .Connected: boolean that can return whether the PC is connected to the internet or not.

TimeOut:
Sets or retrieves an unsigned long integer value that contains the time-out value, in milliseconds, to use for Internet connection requests. Setting this option to infinite (0xFFFFFFFF) will disable this timer.

ReceiveTimeOut:
Sets or retrieves an unsigned long integer value that contains the time-out value, in milliseconds, to receive a response to a request. If the response takes longer than this time-out value, the request is canceled

Default values are zero, meaning , these values are not configured and system defaults are used.