I don't have any Hikvision cameras but I do have a few Amcrest with two-way audio and I had to play with the video settings trying different Amcrest profiles rather than the generic ONVIF profile to get two-way audio working.

I saw one review on Amazon saying you can enable ONVIF for BI support: Great Camera By Steve Rhodes on November 13, 2020 This is an excellent camera. Installation was straightforward. Just make sure when the app is taking you through the installation process, the volume on your phone is turned up al...

That sounds like a pretty large machine for your number of cameras but it should work just fine. I have 17 cameras running at 15fps direct to disk (a few are 8MP but most are 2MP), with Intel GPU offloading and substreams for live view running on an Acer Aspire TC-780-UR11 Intel Core i7 7th Gen 7700...

Send an email to support they should be able to send you your original license key which is what you need not the support key although you do need a current support agreement as well to be on the current version of 5.

I ran my BI server with no monitor or keyboard connected for a few years the only reason I ended up connecting a touchscreen monitor was there were a few times on reboot where the system didn't come back up and I'd have to dig out a monitor and keyboard to hookup to see where it got stuck to know wh...

You can definitely change profiles based on an http get request not sure about disabling but I'm guessing there is a possibility for it.

do you have the same address in both the LAN and WAN fields for your server?

I've not had a problem with those same settings, I recently cloned my weather camera and setup an FTP connection to ambientweather.net for my weather stations camera there as well so that camera is sending updates to both FTP servers frequently.

I get the camera overlays on my exports with direct to disk

I've bought my Dahuas from Andy at EmpireTech for the past 3 years, either via Amazon or by email with paypal. He's very easy to work with and all the cameras have worked flawlessly, even when he orders them specially directly from China they arrive quickly.