Your ‘speed’ in terms of TCP payload speed depends on whether you’re using IPv4 or IPv6 and, if you’re using TCP, whether or not you have TCP timestamps enabled, which is a choice of the operating systems at both ends. In FTTC / VDSL2 the speed also depends on the G.INP setting, efficiency of 96.69% if G.INP is ON and at the normal setting or 91% if G.INP is set to ReTx HIGH (not entirely clear what that is). My spreadsheet tells me that with VDSL2 and G.INP = ON, normal the efficiency of TCP + IPv6 payload should be 92.8% (I think that’s without TCP timestamps, but I need to check the calculations again). TCP+IPv4 will be slightly faster than IPv6 because the IPv4 header is 20 bytes shorter. If you have TCP+IPv6 and G.INP=ReTx HIGH then the TCP payload efficiency should be 87.36%, or 88.57% for IPv4. So it’s possible that you have G.INP ReTx HIGH. If you are getting any retransmissions at all due to CRC errors then you won’t be getting full TCP speed. There could be other reasons why your TCP speed isn’t as high as it could be.