Hiatus

Up until recently I could view and save recordings on my Hikvision DVR (DS-7208HUHI-K1) using iVMS4200 on my Windows 10 PC. and was also able to view live images via my android phone's mobile-data using Hik-connect. I can still view live images on iVMS4200, but can no longer view recordings <Playback failed. No record file found. (Error code: iVMS-4200.Video.C.exe[1617].)>, and can view live images on my phone via w-fi, but not when dependent on mobile data <The device is offline>. There'd been no change to hardware, and as far as I'm concerned, no changes to software or firmware. I have a static IP from my ISP. In iVMS4200, under MAINTAINENCE AND MANAGEMENT, I get <Device status: Cameras 1 to 5 No recording> Under CONFIGURATION, using the S.M.A.R.T hard drive test, iVMS reports <Self-evaluation Pass> and <All-evaluation Functional>, so I'm assuming the hard drive is ok (I have a replacement ready but don't want to add in a component change to an already-confused situation). I can't find information online that applies: many of the articles and videos show views of the iVMS software that do not correspond with my installation (Version V3.1.1.11 build 20190930 latest version), and quite frankly I find the interface overly-complex and the official information near-incomprehensible. I'd welcome advice and will provide further specific information on request!