DN-2000
Displacement: 2,400-2,500 (full load, presumably)
Dimensions: 90.5m long x 14m wide x 4m (7m depth from main deck)
Propulsion: diesel electric propulsion with 4 Caterpillar C3516C, total 12,016 horsepower
Top speed: 21 kn
Endurance: 40 days and nights at sea
Range: 5,000 nautical miles at 'economical speed' (probably 12 to 15 kn)
Crew: 30 persons + rescue team 40 persons
Armament: 2 weapons position for 14.5mm single HMG and 2 for twin 23mm cannon
Modern navigation and communications, including SATCOM
All activities of the vessels are controlled by a computer system.
Landing platform for a 14 ton naval helicopter e.g. Ka-28
Can tow distressed ships with a displacement of up to 2,200 tons
Capacity to house 120 rescued persons.
Two 150-200m range watercannon, capable of spraying 6.6 m3 / minute
Similar, for different agency, with reinforced bow.
http://www.vietnambreakingnews.com/2014/07/vietnam-fisheries-surveillance-receives-modern-ship/
See also
https://www.sinodefenceforum.com/south-east-asia-military-news-reports-data-etc.t5809/page-82
DN-4000
Displacement: 4000 tons
Dimensions: 120 m length x 16 m beam
http://www.viethaingoai.net/canh-sat-bien-viet-nam-se-co-tau-tuan-tra-4.000-tan.1.html
According to Ha Son Hai Colonel - General Director of the United firms said the upcoming Autumn River Song Collection will launch at least 2 new building marine police boat versatile by design DN-4000
Reportedly, last started in 2016, Song Thu completed Partnership signed with the DN-4000 paired first vessel. The vessel will have the displacement of over 4,000 tons, more than double compared with the DN-2000 class ships before.
According to Colonel Ha Son Hai, expected in 2019 the vessel will be completed, handed over to the law enforcement unit of the Vietnam Sea.
http://soha.vn/canh-sat-bien-vn-nhan-bao-nhieu-tau-dn-4000-hien-dai-va-khi-nao-20160412173801248.htm
If that is the DN-4000 depicted, it looks more like a progression on the DN-2000, than based on Holland class.
See also
https://defence.pk/threads/watch-out-china-vietnams-coast-guard-will-fight-back.396938/#post-7632656