Lost internet over LAN?

Question

Computer networks

Actually the problem is the next office of 40 wheelbarrows.
the external line goes to the kerio, then to the switches (in the server room) managed and diverges through the patch panels and then through the sockets.
There is a CD Server 2016.
The subnet is one 192.168.0.xxx both on computers and on MFPs
and the situation is as follows the other day, on some wheelbarrows the Internet falls off, there is physics (there are signals), IP shows, but does not go to the Internet, it is decided as follows: pull out patch cord from the computer and plug or disable the network card and turn it on again. I thought in the network card, no. The computers are new, I replaced the network card - it did not help. Kerio does not throw any errors except microt, which I brought to 1 subnet (192.168.1.1 is an IP microt) for distributing wifi, it gives out IP 192.168.0.xxx to clients and it writes this log:
Anti-spoofing: Packet from local, proto:UDP, len:155, 192.168.1.1:5678 -> 255.255.255.255:5678 , udplen:127 who faced, where to look?

Answer 1

Check the cable and crimp. physics problem.
if these PCs come to one switch - start by replacing the patch cords on the switch and checking the switch itself

Answer 2

The problem is with dhcp. There are two options, either a small pool and different addresses are constantly distributed to different devices, or a second dhcp on the network.
As a result, you sometimes have an address conflict.

Answer 3

Check if you have a left DHCP server on your network. I remember when some smart guy raised DHCP in our place, the network started randomly falling off (1000+ PCs, a dozen or two lost the network), they caught that they got IP from some strange address and sawed it out.

Answer 4

In Kerio, no errors are thrown except for the microt, which I brought to 1 subnet (192.168.1.1 - this is the IP microt) for distributing wifi, it gives out IP 192.168.0.xxx to clients and it writes this log:
Anti-spoofing: Packet from local, proto:UDP, len:155, 192.168.1.1:5678 -> 255.255.255.255:5678
, udplen:127

Obviously you have two mismatched DHCP servers, one interfering with the other. Check your settings.