How to determine the source of an error on Mikrotik (excessive broadcasts/multicasts, probably a loop)?

Question

Mikrotik

Greetings gentlemen.
I've been struggling with this problem for a week now.
In the logs on the Mikrotik RB750GL router, errors periodically begin to appear and all interfaces fall:

Aug/08/2016 14:16:24 interface,warning 1WAN_KTelecom excessive broadcasts/multicasts, probably a loop
Aug/08/2016 14:16:24 interface,warning 2LANMaster excessive broadcasts/multicasts, probably a loop
Aug/08/2016 14:16:24 interface,warning 3WAN_DOMRU excessive broadcasts/multicasts, probably a loop
Aug/08/2016 14:16:24 interface,warning 5IPTV excessive broadcasts/multicasts, probably a loop

The appearance of an error from day to day is chaotic. Today one interface, tomorrow another, the day after tomorrow all together.
I started by looking for a loop, the office is small, I personally went around all the sockets, there are no loops. A couple of switches, one router for test hardware (it has its own subnet inside, which does not intersect with the working subnet)
I completely disabled the port from the local network on Mikrotik, the errors continue.
Blocked incoming traffic on external ports from local IPs.
Turned off external interfaces one by one.
Disabled all rules in the Mangle section, the error continues.
Turned off all rules in the NAT section, the error continues.
IGMP
disabled IPv6 disabled (package removed from Mikrotik)
Never faced such a problem before. Everything seems to be correct in the configurations, I checked the routes and markers several times. Traffic is going well.
But as soon as this error starts to pour, all interfaces periodically fall for a few seconds.
Then they rise, and the error repeats after a while. Rebooting the router saves for a while.
Maybe someone faced a similar problem? Tell me which way to dig?
The traffic was collected by a sniffer during the appearance of errors, opened in Wireshark. I couldn't find anything of interest.
I'm thinking of installing a new router.

Answer 1

В общем не знаю что это было, решил так.
- Откатил настройки восстановлением бекапа двухмесячной давности, при этом он сделал полный сброс перезагрузку и восстановление конфигурации.
- Добавил недостающих правил (которые появились за эти два месяца)
- Запретил доступ локальной сети по UDP портам во внешку (если понадобится в будущем, то выборочно по портам открою). Для VoIP адресов (базы Panasonic) доступ к UPD во внешку без ограничений оставил.
Все. В логах ошибок нет, интерфейсы (порты) не падают. Вторые сутки под нагрузкой работает стабильно.

Answer 2

Здравствуйте! Я наблюдал такую ситуацию, когда к микротику было подключено 5 iptv приставок, и все они работали. Это, по сути, лишь предупреждение о том, что куча бродкаста-мультикаста проходит через интерфейс. Если у вас используется мультикаст в вашей сети - значит, забейте (если не проседает производительность).