In Multi-NIC hardware environments, it is important to remember that the calculation of the HWID is based on the configuration of the NIC when Nx Witness is originally installed. 

If a NIC hardware configuration is modified AFTER Nx Witness perpetual licenses have been activated - for example, if one NIC port is disabled - the HWID will change and licenses will become invalid.

Windows OS Multi-NIC Troubleshooting

1. Re-enable the NIC.
2. Open Command Prompt and enter ipconfig/all
3. Find the re-enabled NIC and copy the Mac Address (a.k.a. the Physical Address) to a text file or clipboard. Change the hyphens in the mac address to colons. 
   Example: B4-AE-2B-3B-FB-A1 to B4:AE:2B:3B:FB:A1
4. Open the Regedit app (on Windows 7 or later)
5. Select HKEY_LOCAL_MACHINE -> SOFTWARE ->Network Optix -> Network Optix Media Server.
6. Find storedMac and double-click to open the Edit String dialog.
7. In the Value data window, copy and paste the Mac Address from above (remember to change the hyphens to colons) and press OK.
8. Restart the Nx Witness Mediaserver application using the Nx Server Tray Tool (located in the lower right-hand corner of the Windows Taskbar) or using the Nx Witness Web Interface.
9. Repeat these steps for all affected NICs until licenses no longer show as invalid.

Ubuntu Linux OS Multi-NIC Troubleshooting

1. Re-enable the NIC.
2. Open the Terminal application and type ifconfig
3. Find the re-enabled NIC and copy the Mac Address (next to HWaddr) to a text file or clipboard. 
4. While still in the Terminal application, type cd /opt/networkoptix/mediaserver/etc and press enter.
5. Type sudo nano mediaserver.conf and press enter.
6. Find the storedMac string and replace the existing value (after the = sign) with the copied value from step 3.
7. Press control + x, press Y, and press enter to apply the changes.
8. While still in Terminal, application type sudo /etc/init.d/networkoptix-mediaserver restart and press enter.
9. Repeat for all affected NICs until licenses no longer show as invalid.