How to beat the network?

Question

Mikrotik

All the best

I don’t know where to dig, the entire network is built on microtics, a tangle of networks, but it worked for almost 5 years. My work coincided with the work of the provider, updates and internal services.
Now there is a problem, the Internet disappears, while the internal network 1.0 / 24 falls down, you can’t even connect to the router, but you can enter the device via MAC. The trouble is that the logs are in order, there are no errors anywhere, there is no swearing anywhere, there is no internet from a minute to five.
Can anyone come across and have ideas

Answer 1

Thoughtfully start drawing the network according to the actual layout.
Perhaps there will be a loop and a switch that can extinguish storms and turn off the port / ports during a storm for a few minutes.
And yes, loops can also occur in a cunning way from a user who has shared his connection (such as has wifi and copper)

Answer 2

I would suggest either a loop (but since mak is available, this is not it) or an address conflict.
Try the following:
1. Hang another address on another network on the same interface and check the availability at this address at the moment when problems occur.
2. Hang another address on another network on another interface and check the availability at this address at the moment when problems arise.
3. At the time of problems, take a dump on mikrotik and on the workstation. In general, in any incomprehensible situations, take a dump from the network, you can find a lot of interesting things there.

Answer 3

Fortune telling on coffee grounds. Give here the config of the head router, in your opinion.

Answer 4

Is there a scheme? If not, you need to build and meditate on the distribution of addresses and the fact that there may be an "extra" dhcp in the network.

Answer 5

Disconnect all segments from the core and start drawing a network map, connecting segments along the way. Check everything carefully every time.
So you can catch the one who spoils everything
First, the segment, and then a specific device or PC ...

Answer 6

Check if there are bridges, then the addresses should be on them, and not on the interfaces that are included in the bridge. It also looks like the ring is somewhere and the moles are tearing it, again, if there are breeches, check the STP on the breeches, try turning it off (put it back later) and see where it stings. When connecting to a mole, pay attention to the CPU usage, if the CPU is eating networking (you will find it in profiling), then this is definitely a ring, do not forget to look at the indicators, they should not blink often and synchronously.