I have made two trips to Vietnam:
Band QSOs Points Zones Countries
160m 0 0 0 0
80m 0 0 0 0
40m 0 0 0 0
20m 465 1208 31 81
15m 394 723 30 66
10m 737 1686 27 83
The problem was electrical noise - I had to close the station down from 18:00 to 00:00 (local time) when the nearby neon lights were turned on as they created S9+ noise across all bands. During the day the electrical noise dropped to S5 so apologies to stations that called but were not heard due to the QRM.