Here: https://docs.opnsense.org/manual/how-tos/wireguard-selective-routing.html#step-9-configure-routing-for-traffic-generated-by-the-router
Q1: Quick=unchecked means that you shall not have any other rule affecting the traffic to the external Authoritative DNS server otherwise this rule could be not effective, correct?
Q2: using a firewall rule to route traffic shouldn't be possible only when the direction is "IN"?
Q3: Source=Select the interface address for your WireGuard VPN (eg WAN_VPNProviderName address)
Destination / Invert=Checked
Destination=Select the interface network for your WireGuard VPN (eg WAN_VPNProviderName net )
here we are telling the system to consider what is exiting any interface + coming from the VPN interface and directed to anything but the VPN subnet....honestly I do not understand this, someone can better clarify this?
Q4: this rule isn't be enough to solve the DNS leaking? (assuming that DNS is managed by opnsense itself) Would it not be best to mention this step again in the "dealing DNS leak" https://docs.opnsense.org/manual/how-tos/wireguard-selective-routing.html#dealing-with-dns-leaks
Thanks!