It sounds like you're running into an issue with your VLAN configuration on your switch. The issue you're describing, where the internet goes down when you try to assign VLANs to different ports, is likely caused by a misconfigured VLAN or DHCP pool.
In order to isolate two VLANs on your switch, you will need to create separate DHCP pools for each VLAN. This will allow each VLAN to have its own unique IP address range and prevent the VLANs from overlapping.
To create a DHCP pool for a VLAN on your switch, you will need to use the following syntax:
service dhcp
ip dhcp pool [POOL NAME]
network [IP ADDRESS] [SUBNET MASK]
default-router [DEFAULT GATEWAY]
dns-server [DNS SERVER IP]
Replace [POOL NAME] with a unique name for the DHCP pool, [IP ADDRESS] with the IP address range for the VLAN, [SUBNET MASK] with the appropriate subnet mask, [DEFAULT GATEWAY] with the default gateway for the VLAN, and [DNS SERVER IP] with the IP address of the DNS server.
Once you have created a DHCP pool for each VLAN, you can then assign the VLANs to the appropriate ports on your switch using the following syntax:
interface [PORT NUMBER]
switchport mode access
switchport access vlan [VLAN NUMBER]
Replace [PORT NUMBER] with the port number you want to assign the VLAN to, and [VLAN NUMBER] with the VLAN number you want to assign to the port.
I hope that helps!
