CX3-40C and CX3-40F management port not working

Hello everyone!

I work in a networking company, and there are CX3-40C and CX3-40F in our customer's datacenter that we should monitor every month. Until October 2023, we were able to monitor them using a PC in the datacenter that is setup and connected to both storages. However, the connection disrupted suddenly at some point that we do not know. We even tried to connect our laptops using LAN cable to the management port of the storages and setting up our laptop's IP address in the same subnet as we used to. However, that does not work too. 

What could be a problem in this case? Is there any other way to connect to the management interface of those storages, maybe using serial cable or something? Or maybe using a controller server that is connected to them?

Thanks!