@chrisb306 check any firewalls and disable to test, see my post as got another hik working now with gateway.
Also ensure substream is set to lowest res.
It used to be that cameras were VGA resolution and that was easier to handle on wireless connections. The RLC-411WS has a resolution of 2560x1440 and a bit rate of about 6144K bps. That’s a lot of data and excellent for reading those auto license plates at distance if you need to zoom a frame. The downside is that on a wireless connection, you will drop frames due to environmental conditions. Consider wiring those cameras. I have three Reolink cameras on my NVR which is a QNAP NAS.