@lleachii
Thanks a lot for your help.
Here's what I've done:
I already had, in OpenWRT, a VLAN with VLAN ID of 3 (10.230.2.0), that I created using this tutorial. I tagged the LAN 4 port on it, as funny enough it was the one I wanted to use, and also tagged it in VLAN 1 (10.230.0.0), just like on your image. Then, in the Netgear Switch, I created a VLAN with VLAN ID of 1, and another with a VLAN ID of 3, just like in the OpenWRT Router. The cable coming from the OpenWRT Router, connected to the Switch, was connected to Port 1, so, I tagged this port in both VLANS, and untagged the ports that I wanted to use for each VLAN. Here are some screenshots:
https://imgur.com/a/MbGQFCF
The VLANS in the Netgear Switch:
I cannot take a screenshot right now, but they are configured as follows:
VLAN ID 1 - Port 1 tagged, Ports 6,7 and 8 untagged;
VLAN ID 3 - Port 1 tagged, Ports 2,3,4 and 5 untagged;
Port 1 is the one connected to the router, in LAN 4.
I did all this, and devices connected any of the ports, even to ports untagged for VLAN 1, all get 10.230.2.x addresses, which is for VLAN 3. Any ideas?