Greetings everyone,

I'm encountering an issue with Power over Ethernet (PoE) on the Mikrotik CSS610 netPower Lite 7R Switch. I've deployed over 30 of these switches, and initially, I installed multiple PoE adapters to ensure stable power. However, lately, I've been experiencing power instability with the switches randomly turning off. Upon investigating the problem, I discovered that the switch is only receiving PoE from one Ethernet port, despite the requirement for a minimum power input from three ports.

You're referring to 2 different products:
CSS610
and
netPower Lite 7R

Which one is giving you problems ?

CSS610 only accepts one power input using AC adapter.
netPower Lite 7R does accept 3, one of them being POE on 7 of 8 ports.

I MEAN netPower Lite 7R - 7 port of the switch give poe in and 1 port is poe out

You're referring to 2 different products:
CSS610
and
netPower Lite 7R

Just for info, the netPower Lite 7R is one of the CSS610 range - its full model name is CSS610-1Gi-7R-2S+OUT

I discovered that the switch is only receiving PoE from one Ethernet port, despite the requirement for a minimum power input from three ports.

Power is only taken from the input with the greatest voltage, each input should be capable of providing all the power necessary to operate the switch itself, any SFPs and device supplied by the PoE out. Where does this requirement for power from a minimum of three ports come from?