The applications and configuration you should setup first thing out of the box.
My page here explains how to integrate synology community packages into the Package center.
Control Panel Advanced Mode
In the top right corner of the Control Panel click Advanced Mode to allow you to see all of the Control Panel options at a glance
Disable the Admin and Guest Account
Once you login, you should create a new account for yourself, set the password and give yourself the admin role. After that, open Control Panel/User and disable the default admin and guest account.
Its not a good idea to leave default accounts enabled. If default accounts are enabled, attackers only need to hack the password since they already have the user names.
I’m not sure how much of a security concern this is, but it is super convenient to access your NAS from outside. From Control Panel/QuickConnect check the Enable QuickConnect box. I don’t remember the exact process, but you’ll need to associate it to an external user account, create an id and I believe you may need to create a default certificate.
One the Advanced tab, I also allow relay and port forwarding and allow access to all of the applications since I do use some of the mobile applications.
In Control Panel/Network, I like to set DNS server manually. Here I like to use cloudflare DNS servers (126.96.36.199/188.8.131.52). I also set the server name because this can make it easier to find on your home network.
On the network interface tab, I have created a bonded connection. I hooked two different ethernet cables into the NAS. I don’t remember the exact process for creating a bonded connection (I will have to cover that in a different section). I don’t think this does much unless you have a computer that has a bonded connection on the client side. It might help if you have two clients that are accessing the NAS at the same time. I’m sure someone in the comments will tell me when this is a useful feature. I had an extra open port on my switch, so I thought I might try this out.
On the DSM Settings tab, I select automatically redirect http to https (and I think you may need a certificate for this).
Always enable dark theme.
Set your timezone and allow NTP service.
Hardware and Power
IMPORTANT: allow Restart automatically after a power failure. If you do not allow this your NAS will NOT restart if it gets powered off.
I have my NAS in a closet, so I enable Cool mode.
I do setup Reverse Proxy. I describe that here.
In Terminal & SNMP, enable SSH.