I have some brix with realtek and run ptpd installed with fedora 25. The corrections are in the 25 microsecond range, though there are anomalies. These are used for wifi DUTs that go into RF enclosures.
[root@hera ~]# tail -n 1 /var/log/ptpd2.stats
2017-11-04 18:33:46.723476, slv, 0cc47afffea87386(unknown)/1, 0.000000000, -0.000018381, 0.000000000, -0.000018463, 1528.032750001, S, 0.000000000, 0, -0.000018988, 1403, 1576, 17, -0.000018463, 0.000000000
For LAN/WAN traffic, I tend to use the intel quad server adapters in a supermicro mb desktop with 8 or more real cores. (I think the data center class machines are worth it.)