Im running my network for quite some time and it was working fine until a couple of days or so. Im not quite sure but it seems to be related to a RouterOS upgrade on a CRS125-24G-1S
2021-04-06 00:39:32 system sw05.kmp1 OS Version: 6.47.8 -> 6.48.1
I have found the following change in the versions
Release 6.48
*) bridge - added fixes and improvements for IGMP and MLD snooping;
*) bridge - added minor fixes and improvements for IGMP snooping with HW offloading;
*) bridge - fixed link-local multicast forwarding when IGMP snooping and HW offloading is enabled;
*) winbox - added missing IGMP Snooping settings to "Bridge" menu;
Release 6.48.1
*) crs3xx - improved system stability when bonding and IGMP snooping is used (introduced in v6.48);
My network is equiped with a Cisco 2960 which is connected to the access points (the hold several Chromecast devices) and a Ubuntu Server which runs AVAHI-Daemon a mDNS reflector to connect the wireless vlan to the wired vlan. The Cisco is also connected to the CRS125-24G-1S which holds my laptop and HomeAssistant PC
When i connect my laptop to the Cisco TCPdump is actually showing me the mDNS traffic, so the mDNS reflector is working fine
root@eggshell:~# tcpdump -ni enx0050b6e5ab2a host 192.168.110.244 and not port 22
When i connect my laptop to the Mikrotik TCPdump is NOT showing me any mDNS traffic!
root@eggshell:~# tcpdump -ni enxc8f7507bc3d1 host 192.168.110.244 and not port 22
BUT, as soon i disable the IGMP Snooping on the Bridge the mDNS traffic is flowing and the Chromecast are discovered
[admin@sw05.kmp1] /interface bridge> print
Flags: X - disabled, R - running
0 R ;;; created from master port
name="bridge1" mtu=auto actual-mtu=1500 l2mtu=1588 arp=enabled arp-timeout=auto mac-address=4C:5E:0C:00:85:D3 protocol-mode=none fast-forward=yes igmp-snooping=no auto-mac=no
admin-mac=4C:5E:0C:00:85:D3 ageing-time=5m vlan-filtering=no dhcp-snooping=no
[admin@sw05.kmp1.raqxs.net] /interface bridge>