How to force active directory replication from one DC to another
Solution 1:
It probably is a recent addition of LiveQoS NDIS Filter Driver
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Uncheck the filter on your IPv4 NIC and reboot your servers to be sure. I bet that fixes your problem.
Solution 2:
Its not clear what the immediate cause of your issues is, but one thing that jumps out at me is the presence of a 'NDIS Filter Driver' on both your servers' NICs. These drivers are often installed by AV, but in your case seem to be from some sort of QoS software. Filter drivers are a common cause of network issues in Windows.
I'd try disabling or uninstalling the LiveQoS NDIS Filter Driver, rebooting and testing again. Also you don't say whether you've run dcdiag.exe, which would be one of the first things I'd run when troubleshooting AD. Consider running that and posting any errors here.