This was pretty good advice!
My connection had ground into the floor (speedtest: ping 1865ms DL 0.6Mbps UL 0.13MBps) so I did a test.... I unplugged the PCCW modem and replugged it and retested: new ping 23ms DL 6.56MBps and UL 0.47Mbps.
Then I booted up the smartone modem and connected to that - this was is giving ping 46ms DL 2.41Mbps and UL 1.06Mbps.
So the smartone is better than the "clogged up" PCCW but slightly worse than the "refreshed" PCCW.....