Why does Mikrotik sometimes go into bridge mode?

Question

Computer networks

Good afternoon.
I have Mikrotik 2011UiAS. Firmware 3.24, Package version 6.31.
The provider distributes the Internet via DHCP, with binding to the poppy address.
In the first LAN port - a cable from the provider is connected.
In 2-3 - servers. At 4-5 switches.
Eth2-5 bridged.
There is access to the network, but after a while (the last time it was 21 days ago), the router for some reason switches to bridge mode. The provider receives a bunch of poppy addresses from us and the network falls outside. Everything works inside.
What can cause it to go into bridge mode?

Screenshots if needed

Настройки роутера

То, что получает от нас провайдер

Moreover, if you restore the last configuration from the backup, then everything still works.

Answer 1

You have some kind of wrong mikrotik. Maybe someone rebuilds the thread? ;)
Change passwords, block access from the outside, disable mac telnet server with wan interfaces.
Make sure you eat well.
Does not help - try to change the piece of iron.
Well, yes, upgrade to the latest stable firmware ...
In general, standard actions, gentlemen.

Answer 2

and eth2 does not have the value eth1 in the master-port field?
I would say that it is worth changing passwords and cutting down unnecessary ip-services;)

Answer 3

Try to disassemble the bridge and use hardware switching, for this, select master port eth2 for the eth3-eth5 ports.

Answer 4

compare the text config from the backup and the text config