windows firewall?
Windows FW disabled for Private network ( that is the case) and MP autorised for both Public and Private. There are 2 difference between PC , the Remote NDIS driver : 10.0.18362.1 on the problematic PC (10.0.16 on the good one) and Windows French (et Oui) on the problematic PC.
I will try with another PC this week ,but the UNKNOWNED Header on the Mavlink ID message should be investigated == SysID 1[0]:UNKNOWN(27)
Is that sysid 1 compid 0? If it is it’s the ping chip for adsb