[OpenWrt Wiki] VLAN
https://openwrt.org/docs/guide-user/network/vlan/switch_configuration05.11.2021 · Newer devices with embedded switches (like Netgear R7800) use the DSA switch driver, that creates a distinct network interface for each switch port as if they didn't have a switch at all. Most OpenWrt-supported devices can use the DSA driver, but they aren't ported over yet because the switch configuration would change significantly and likely break any custom setup …
[OpenWrt Wiki] Switch documentation
openwrt.org › docs › guide-userAug 02, 2021 · The tests seems to confirm that because (using a vmware switch and portgroups) to let two openwrt x86 vmware guests reach each other the portgroups had to be configured with the trunk vlan id (that is: vlan id 4095, According to white papers: VMware Virtual Networking Concepts and VMware ESX Server 3 802.1Q VLAN Solutions).