Seeing it on your PC
svchost.exe on port 68 talking to your router on 67 is your PC asking for, or renewing, its address.
Should you block it?
Leave it alone. Blocking DHCP drops your PC off the network when its address lease runs out.
Check it on your PC
Run this in PowerShell to see what is using port 67 right now, and which program owns it:
Get-NetUDPEndpoint -LocalPort 67 -ErrorAction SilentlyContinue | Select-Object LocalAddress,LocalPort,@{n='Process';e={(Get-Process -Id $_.OwningProcess -ErrorAction SilentlyContinue).ProcessName}}No output means nothing is using the port at the moment. For every connection at once, paste netstat -ano into the netstat explainer.