There is a 3 µs offset between master and slave's 1PPS. What do I do?
This happens when one of the devices (master or slave) is connecting to the Ethernet network at 100Mb and the other device is connecting at 1Gb. The 3µs comes form the difference in the amount of time it takes to transmit a packet at 100Mb vs receive at 1Gb or vice versa.
Check the link speeds of the connected devices.