Follow Gschwinds' link.
Some things to consider regarding security:
1. run security advisor and implement tips (the next two points should also be pointed out by the advisor).
2. deactivate admin account and give your user administration rights with a strong password.
3. change standard ports (5000-> http, 5001->https).
I would use something in the 4-digit range...
4. settings security -> switch on firewall, auto block, (DoS protection).
Basically, if you can access it from the outside, so can anyone else who knows what they are looking for, and if someone is looking for poorly protected Synology NAS, they will check ports 5000 and 5001.
Theoretically, you can also allow only IP addresses from Switzerland in the firewall, as long as you don't want to access it from abroad.
There is a list on Synology which external disks support hibernation mode.
Go to Settings > Hardware and Power > Hard Drive Hibernation > Set USB Hard Drive Time. Then the hibernation mode should work P.B