pfSense

Unable to reproduce:

lagg0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0 mtu 1500
    description: OPT2
    options=6900bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,VLAN_HWFILTER,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6>
    ether de:e1:87:63:8d:8a
    inet6 fe80::dce1:87ff:fe63:8d8a%lagg0 prefixlen 64 scopeid 0xc
    laggproto lacp lagghash l2,l3,l4
    laggport: vtnet3 flags=0<>
    groups: lagg
    media: Ethernet autoselect
    status: active
    nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
lagg0.11: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0 mtu 1500
    description: VLAN11
    options=680003<RXCSUM,TXCSUM,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6>
    ether de:e1:87:63:8d:8a
    inet6 fe80::dce1:87ff:fe63:8d8a%lagg0.11 prefixlen 64 scopeid 0xd
    inet 10.22.22.100 netmask 0xffffff00 broadcast 10.22.22.255
    inet 10.22.22.22 netmask 0xffffff00 broadcast 10.22.22.255 vhid 1
    groups: vlan
    carp: MASTER vhid 1 advbase 1 advskew 0
    vlan: 11 vlanpcp: 0 parent interface: lagg0
    media: Ethernet autoselect
    status: active
    nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>

after changing the LAGG mode from LACP to ROUNDROBIN:

lagg0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0 mtu 1500
    description: OPT2
    options=6900bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,VLAN_HWFILTER,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6>
    ether de:e1:87:63:8d:8a
    inet6 fe80::dce1:87ff:fe63:8d8a%lagg0 prefixlen 64 scopeid 0xc
    laggproto roundrobin lagghash l2,l3,l4
    laggport: vtnet3 flags=4<ACTIVE>
    groups: lagg
    media: Ethernet autoselect
    status: active
    nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
lagg0.11: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0 mtu 1500
    description: VLAN11
    options=680003<RXCSUM,TXCSUM,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6>
    ether de:e1:87:63:8d:8a
    inet6 fe80::dce1:87ff:fe63:8d8a%lagg0.11 prefixlen 64 scopeid 0xd
    inet 10.22.22.100 netmask 0xffffff00 broadcast 10.22.22.255
    inet 10.22.22.22 netmask 0xffffff00 broadcast 10.22.22.255 vhid 1
    groups: vlan
    carp: MASTER vhid 1 advbase 1 advskew 0
    vlan: 11 vlanpcp: 0 parent interface: lagg0
    media: Ethernet autoselect
    status: active
    nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>

Please provide more details about this issue.

Tested on 22.01

I was able to reproduce this bug.
I've created HA cluster with LAGG interface on each node and 30 VLANs on these LAGG ports.
Changing LAGG type made HA cluster very unstable:
- after changing LAGG type 'Interface LAGG edit' page started to reload and finally I got '504 Gateway timeout'('gateway_timeout.png') but in /Status/Interfaces I saw that LAGG type were changed correctly and were changed immediately.

- I got 'CARP has detected a problem and this unit has a non-zero demotion status...' message and most of VLAN CARP VIPs were in INIT state (see attached 'first_error_after_changing_LAGG_type.png')

- after pressing 'Reset CARP Demotion Status' most of VLAN CARPs were in INIT state ('after_pressing_Reset_CARP_Demotion_Status.png')

- HA cluster were unstable - some ports of Primary were Master, then they became Backup and then Master again. I always got 'CARP has detected a problem and this unit has a non-zero demotion status...' messages. Step by step, after each pressing 'Reset CARP Demotion Status' the amount of VLAN CARP VIPs in INIT state became less and less ('after_about_10_minutes.png')

Primary node continued to switch to Backup mode and back again and again.

- and after about 20 minutes all VLAN CARP VIPs on Primary became Master and HA cluster became stable.

- pressing Save (without changing anything) for LAGG port, while HA cluster were unstable, change nothing (it didn't make HA cluster stable).

- after rebooting Primary node just after changing LAGG type on it (and getting unstable HA cluster), all VLAN CARP VIPs became Master and HA cluster became stable.