If the NAT speed is not fast enough, even the port is 1000Mpbs, it will not delivery enough speed. (e.g. some old router with slow CPU/ signal chips and 1000Mbps connection can deliver up to only 2xxMbps with lan cable connected.) My problem is whether the port can really deliver 1000Mpbs or I should request a optical modem only box.
I call the PCCW hotline but the service guy was foolish.
Anyway, I would bring a ASUS router to the site and test. The router can deliver download speed up to around 950Mbps with a 1000Mbps HKBN connection (modem only).