Convert server downtime to Uptime in Hours for whole month

New to the site and new to excel so hope someone can help. I have downtime start date to downtime end date, which generated by system.

I would like a way to record on a daily basis what the uptime has been for each server and then to record the same for that month in a hours… The time always started at 6.00 AM to 6.00 AM next day everyday. Maybe you could edit the attached file for more clear understanding on my problem.

Appreciate if someone can guide me.

Thanks.