I installed opnsense on an i5-6500T (native, no vm) but it looks like the performance is very bad, most websites are timing out.
everything is turned off, there's no packet inspection or blocks, even the unbound dns server is not used (using a DC for that)
it's the computer that's underpowered, or i did some mistake in configuring it? Using two routers in the networks for my convenience
You can still do the setup nearly the same, but you'll need to change the opnsense LAN to its own unique subnet, and put PC2 on that subnet with a manual IP setup.
Make sure you don't enable DHCP on opnsense too, since that will really interfere with the existing router.
The only real downside to this, is PC2 traffic to access PC1 or other devices on the main router, will have to go through opnsense and you'll need firewall rules for that.
After you mentioned that I checked now and in opnsense DHCP leases they're all in wan and not in LAN
LOL what I mess I created...