Working with VLAN

Doing my first steps and trying to configure and understans how this works and seems found one tiny BUG:
Debian Bookworm
NIC card configuret for 2 VLANs native for data, .20 for MESA with Layer3 switch.

# The loopback network interface
auto lo
iface lo inet loopback

# Management interface
auto eno1
iface eno1 inet static
    address 192.168.4.50
    netmask 255.255.255.0
    gateway 192.168.4.1
    dns-nameservers 8.8.8.8 1.1.1.1

# MESA P2P interface (.120-.121)
auto eno1.20
iface eno1.20 inet static
    address 192.168.1.122
    netmask 255.255.255.252
    post-up sysctl -w net.ipv6.conf.eno1/20.disable_ipv6=1

Seems like its trying to reach a wrong folder during startup..
Note: Using POSIX realtime
sysctl: cannot stat /proc/sys/net/ipv6/conf/eno1/20/disable_ipv6: No such file or directory

the right place is: /proc/sys/net/ipv6/conf/eno1.20/disable_ipv6

Debian issue, not LinuxCNC, so might be better to post this on their forums, if you feel like it.

If LinuxCNC fails to verify that IPv6 is disabled and looks for the script/path in the wrong place, that is rather a software bug, not an OS issue.

1. everything related to networking is Debian
2. pretty sure LinuxCNC does not use IPV6 at all
Remove this line

It would be much easier to ditch the vlans, flick the switch on the Mesa card so it is set to 10.10.10.10
And set the PC's NIC on that segment to be 10.10.10.1
Please read man hm2_eth on how to set this up.