Using the exact same config under 1-18-0 is solid.
I have dropped CTCM speed down from 90Mhz to 75 but have the same issue.
I get the same problem whether I use the SVethlana or EtherNAT (I only use one XIF at a time as dhclient doesn’t appear to support multiple adaptors). Note that I am using the drivers included in the trunk distribution, the only files I have pulled from my 1-18-0 folder are mint.cnf, xaaes.cnf and svethlan.xif