Is the PC network cable connected directly to the LAN port of the router or through the ethernet wall socket or other device?
Try to reset network connections: Open PowerShell or CMD and run as administrator, copy and paste the following commands by pressing enter at the end of each command line:
netsh winsock reset
netsh int ip reset
netsh advfirewall reset
ipconfig /flushdns
Restart the computer at the end of all commands.
If that doesn't work, try resetting the network:
Start>Settings>Network & Internet>Advanced network settings>Network reset>Reset. Follow the instructions.
Specify whether you are using Microsoft or third-party Firewall/Antivirus.