I'm not familiar with the Server versions of Windows and not sure that the program should be run on those versions.
I've asked for advice on this.
There is a cmd you can use from a Command Prompt run as an administrator and that is netcfg -x
If you run a cmd prompt as an admin and enter netcfg /? you will see the list of cmds you can use and what they do.
However, I think I would opt for booting into Safe Mode and use the Registry Restore option in the repair program to see if that reinstates your LAN.
When you get to that pane, click on the Registry Restore tab and use the dropdown to select the back up and then hit the Restore Now button.
There are a number of things that can cause performance issues - one has already been addressed in the repairs and that is to clear the Temp folder cache.
After the restore and I can only describe the procedure for Windows so you will need to equate to your system if required, go Start - type %temp% and click on temp file folder.
If that is highly populated, press CTRL+a to highlight then CTRL+d to delete - confirm then check the box and click on Skip.
If there's still a high volume in there, then repeat the procedure.
I'd also check your Start up items as having unnecessary programs running in the background will unnecessary take up memory.
Check to see if the HDD needs defragging - you can perform a defrag by using the cmd defrag /c from an elevated cmd prompt.
An infection can also impact on performance, so a scan with a robust antimalware scanner would be advised.
In addition to my Norton Security I use the free version of MBAM -
https://www.malwarebytes.com/mwb-download/You can use the standard scan but I would suggest that you click on Scan in the left pane and select Custom Scan/Configure and check the box for C:
This will do a full scan and can take a while to run.
In the pre-steps to running the repair program, did you perform a chkdsk /f or sfc /scannow from an elevated cmd prompt ?
The chkdsk will tell you if you have any bad sectors on the HDD in which case you should image your system ASAP in preparation for its complete failure and a sfc /scannow will tell you if there are any problems with your system files.
Which antivirus program are you using because some 3rd party ones can also impact on performance as they become bloated.
I've seen this reported for AVG and occasionally Avast can cause problems.
I another instance, the pro version of Bitdefender reduced on e person's machine to a crawl.
I hope that some of these suggestions will help.