pc2pc-windows10

Direct connect between 2 PCs over a second Network Card (2,5 GBe or 10 GBe etc.)

1. Build in Network Cards and Install newest "NATIVE" driver
2. Connect the too Cards with an Network Cable (no CAT5e or similiar Bullshit!)
3. PC1: IP-Address: 192.168.240.1 Netmask: 255.255.255.0 Gateway: - DNS: - / you can use IPv6 in the same way
4. PC2: IP-Address: 192.168.240.2 Netmask: 255.255.255.0 Gateway: - DNS: - / you can use IPv6 in the same way

Group Policies / Firewall Rules (on both PCs!)
5. Press the Button with the "Flag of Pain"(WinKey) and enter gpedit.msc and open it by pressing enter.
6. "Computer Configuration" -> "Windows Settings" -> Security Settings -> "Network List Manager Policies"
7. Under the Set of "Unidentified Networks" change "Location typ" to "Private" and "User permissions" to "User can change location"
8. Press the Button with the "Flag of Pain"(WinKey) and enter Firewall and open it by pressing enter.
9. In the left Side Menu "Advanced Settings" "Connection Security Rules" "New Rule" "Custom" "These IP Addresses" "192.168.240.0/24" and the same for second field.
10. "Do not Authenticate"  "Protocol any" and leave all types activated and set the rule name. 

Finish
test it with ping the other side and viceversa