I assume the clock was showing the correct date and time ?
Have you run an antimalware scan on the machine.
I would normally advise booting into Safe Mode with Networking and running a scan with the ESET Free Online Scanner.
https://www.eset.com/uk/home/online-scanner/I'd also advise a scan with AdwCleaner -
https://www.malwarebytes.com/adwcleaner/I assume you both know that in Win 10 that wireless is turned off in that mode and you'd normally Ethernet connect.
However, if that isn't practical with a desktop PC then you can manually reconnect to wireless.
When you first boot up into that mode and you have the desktop screen, press CTRL ALT DEL - click on the wireless icon and then on your SSID and then on Connect.
Left click away from that pane to close it then click on Cancel where you will then see a full wireless icon.
If this was my machine there are a couple of procedures I would try but each require Win 10 install media.
Install media, either a DVD or USB can be created after reading
https://www.microsoft.com/en-gb/software-download/windows10I would first boot up with the install media which requires changing the boot order.
This can be done as a one off by tapping F12 as you switch on and using the cursor keys to select the disk drive or USB, but if using an USB then it is best to insert that before tapping F12.
Press enter when the selection has been made and the media is inserted.
If using a DVD then you are normally prompted momentarily to press any key to boot from CD or DVD.
When using a DVD you can be presented with an inverse screen with Windows Setup [EMS Enabled] highlighted - just press enter.
Use the dropdown to change or confirm the keyboard and currency then on the Install screen, select Repair your computer.
Click on Troubleshoot/Advanced options and select Command Prompt.
Enter bcdedit |find "osdevice"
For clarity that is a Pipe symbol before find and is the uppercase of \
Then using that partition letter instead of the X I have exampled, enter -
sfc /scannow /offbootdir=X:\ /offwindir=X:\Windows
Note the space before each /
Depending upon the amount of corruption as to whether either of those will work as I've recently come across where neither did because of corruption caused by an infection.
That may or not fix the corruption, but removing the install media, rebooting and trying the dism /restorehealth and sfc /scannow cmds again in normal mode will show if that is the case.
The second method I would use is a repair install which doesn't affect personal stuff or installed programs.
With the machine booted up, open Windows/File Explorer - This PC - insert the install media and double click on its drive.
This will start the process when using a DVD but will open to its files when using an USB where you would then double click on setup.exe Application.
This can take 3 - 4hrs.
Hopefully, either will resolve the machine's problems.