Win XP and Win Server 2019 Mapped Drives Issue

We have 3 different PCs that are connected with laser cutting machines. Two machines are Win XP and other one is Win 7. 

They are connected with each other on 192.168.100.X network and their default gateway (router) is 192.168.100.200. This router is connected to the main Cisco switch.

We also have a Win Server 2019 with IP address in 192.168.0.X network and connected to main Cisco switch. There are two different folders that are in server and mapped on all three of machines for the operator to load files into the machines.

Everything was working fine from almost a year but from last Thursday, randomly both Win XP machines drops the Mapped network drives but Win 7 machine stays normal.

When we start the server, the mapped drives come back online on Win XP machines. 

Can anyone suggest what could be the issue. Any help on this would be appreciated.

Addition information:

• We have checked the physical connections and all the physical devices, no issues with them.
• The Server has SMBv1 enabled. There were not updates on the server since mid 2022.
• When the mapped drives disconnect, we can still ping machines and RDP into them from Server. 
• Tried restarting the machines but it didn't work. 
• Antivirus program is turned off on Server and machines. Firewall also has Any-Any rule enabled.

   

  Please let me know if you require more information.