Scheduled sleep and wake for HP Microserver Gen8/Lubuntu 16.04?

[itm]

I have an HP Microserver which I'd like to schedule to go into sleep or hibernation at the same time each day, then automatically wake at the same time the following day. I've tried this command to check basic sleep/wake functionality, but it doesn't wake the machine as intended:
sudo rtcwake -m mem -s 10 && firefox

Can anyone suggest a way of achieving what I'm trying to do?

 

[itm]

Hmmm...this is strange...I just tried this:

sudo rtcwake -m mem -s 120 && firefox

...and got this error:

rtcwake: unrecognised suspect state 'mem'

??

 

[itm]

I don't see those "Power on" options anywhere in the BIOS either (they are not shown anywhere in the menu options below "Power Management Options"

 

[itm]

I don't see those additional ACPI options in my BIOS - screenshots of the Power Management Options and Advanced Options are attached.
There's a Wake-on-LAN option under the Server Availability menu, which I have enabled.