latest hikvision firmware

Hello - I'm struggling to find any updated firmware that will work for an NVR I just purchased in the UK. It was shipped with V3.4.104 build 191118 but there doesn't appear to be any trace of that firmware version on the Hikvision portals. I have tried all of the K2 variants here but I get...

Update 7th May 2019 - Superseded by a new V4.21 firmware version - new thread here: Latest HikVision Firmware for -I NVRs - new V4.21 (76XX, 77XX, 96XX NI-I) Please Note - there have been many reported issues arising from the latest firmware releases, and therefore please see our latest...

Update 25th February 2020 - Superseded by V5.6.4: Latest HikVision Firmware for G1 Series cameras - version V5.6.4 HikVision released new firmware for the EasyIP 3.0 / G1 Series family of cameras yesterday 25th March 2018. Available to download from their European Download Portal here...