This problem just started for me. Sounds like a software update had a bug. Just for clarity, here is what I am experience now (this is new; haven't had an issue for over a year). My cameras are all hardwired. When I access them from inside my home network using a browser, I can pull up any camera, no problems. Live action, playback, everything - no issues. My new issue is that effectively my cameras "crash" when I try to view the output using the Hik-Connect Apple IOS Map. Now, when I say crash. I pull up my camera list and select any one of them (I have 6). For 2 seconds, the image looks fine. Then I get a message "Network is unstable. Connecting again." I see that message for a few more seconds and then the message changes to "The device is offline". At that point all of my cameras go offline (and I can't even access them from my PC browser). When they come back up, there is a gap in my recordings that corresponds with when the cameras were rebooting. If I try to access them again once they come back up, it just repeats.
I have never seen this before, so I am highly confident someone at the developer's table screwed up; I'm done fighting it and trying to find work arounds - I guess I'll wait for HIK to fix it.
I just checked the App reviews in the apple store for the latest published version - 2 weeks ago - and there is nothing but people posting that it is crashing their systems. Seems we are not alone...