The light blinked, computers stopped receiving IP from DHCP, how to get it back?

Question

network hardware

Good day to all!
What we have:

• Router Mikrotik rb951ui-2hnd
  
• HPE 1410-24-R Switch
  

Everything is set up near-standard, a DHCP server was raised on Mikrotik, the light blinked and most PCs stopped receiving IP (the network is assigned 169.254.x.x), but 3 computers remained surprisingly available.
Rebooting the router/switch does not help.
Actually, the question is, how can you get client PCs to receive IP without resorting to manually assigning IP?

Answer 1

1) Use UPS for network equipment.
2) Without a Mikrotik config, one can only guess (for example, there are no entries in the ARP table and therefore Mikrotik ignores unknown equipment)
Go through Winbox further IP -> DHCP Server -> Leases and delete all entries (if there are any), then try booting one of the computers that Mikrotik did not see and look at the table and logs of Mikrotik.