@ethan118 

1. Yes it's suggested to use an IP out of your DHCP range, to prevent IP conflict.

You can put in Gateway 192.168.0.1 but it has nothing to do with client devices' Internet. The gateway of the switch will be useful if you have multi-nets network or, your 2nd request Remote Management

2. You will need to do Port Forwarding on the Router, open port 80 for the switch IP.

If you use DDNS please note the router default web interface port is also 80, you need to change router's port so the switch can be reachable on port 80;

3. It seems like a new hardware version so no new firmware update. 

The setup I have is I use my ISP modem/router then connect it to my TPLINK router. I did port forward port 80 from ISP modem/router. At the moment I have not done this on the TPLINK router because I have used all my port forward and max out. All 32 port forward I have used for mostly IP cameras and few ports for computers remote access. I wonder if I can use Port Trigger for port 80 if I must do this with the switch ? How do I connect to the switch remotely outside my network ? I do not see any DDNS option to add in the switch. Uusally you will put the no-ip ddns login details somewhere.

  @ethan118 Switch is in local LAN network so it won't support DDNS.

If you really need to access the switch from Internet, and no port forwarding can be done on the router, you may consider replace the switch with Omada managed Switch.

Omada switch can be managed by Controller, can Controller is accessible via Omada cloud website.