Yes, you can set an IP range this way :
- open the AdminTool,
- click "Settings and license"
- then go to "IPs Whitelist"
You can use IP ranges like 192.168.1.0/24 and 192.168.1.12-192.168.1.18
An example with the subnet mask 192.168.1.0/24 :
You will have and IP range of all IPs from 192.168.1.1 to 192.168.1.254
Other example with the subnet mask 192.168.1.1-192.168.1.10
This means you have whitelisted all IPs from 1 to 10.