Due to the preferred handling of individual packets, the original packet order is changed. Although TCP/IP does not ensure a certain packet order, problems may result in a few isolated applications. This only concerns applications that assume a certain order that differs from the protocol standard. In this case the SYN/ACK speedup can be deactivated:
LANconfig: IP router / General / Pass on TCP SYN and ACK packets preferentially
WEBconfig: LCOS menu tree / Setup / IP router / Routing method / SYN/ACK speedup