I see that happen when I change a characteristic of the camera's video, such as applying a 90-degree rotation in the camera's own menu. Since you're undoubtedly not causing it yourself, you might experiment with the keyframe interval as a starting point. A setting of one keyframe per second is a good place to start. You could also experiment with a different encoding format (H264 versus H265).
I have a Hik camera inside the house that I don't really care about, but that same thing happens from time to time. It is actually using a 'power over ethernet' adapter and I just attributed it to that
I have been using BI-4/5 for years now, and have been thru it ALL! I consider myself an expert! The issue I see, is something I experienced, similar, which was serious pixelating during a PAN to the right! I have a Jennov 1080P 30X and a Hosafe 1080P 5X, and here is what I have found, and I have resolved any and pretty much all issues, in order of importance!
1) Turn OFF ONVIF...... (done to both my Cameras) Both Cameras are connected by manual IP inspect, using the "Foscam FI86xx/98xx compatible" (I couldn't find any other to work right).......NOT Jennov or Hosafe, OR ONVIF! I use "Advanced Port Scanner," and my
Router Network Map to find changed IP address which is what the DHCP, does! I tried turning to Fixed IP and that didn't work on the cameras really well!
2) Get rid of WiFi and go direct via Ethernet, and here is how I do it: I did get a cheap POE Inserter cable M/F, on EBay, so the farthest camera gets power from the UPS feeding the closer camera! NOT 48V POE, just I breakout the 12 volts at the other end and use the DC input!! The RE500 and the 5 port hub, also on UPS!
3) After much test to get connection from Garage to my office, is my latest fix that has resolved everything, is a 5 port hub switch in the Garage connected to a UPS, ($15.99 TP-Link Gigabit at Amazon-both camera plugged into it) with an Ethernet cable to a top quality
TP-Link Range Extender (RE500) about 20 feet closer, in the garage, connected to the Ethernet Port) The WiFi on this extender also has my Orbit Sprinkler Controller, a House HVAC Thermostat, and a TP-Link Smart ac outlet controller, all on 2.4Ghz!
4) My house is 3000 Sq', and my Linksys Router is in my office thru many walls, at the farthest point! I recently swapped out all 4 antennas for 4 12DBi gain antennas from EBay! They are huge! 15" high, work great!
5) I was experiencing multiple disconnects and I even took the "Watchdog Setting" down to bare minimum, just to get BI-5 to reconnect quickly! That has all gone away! Rock SOLID!
6) My Pans up or back are totally clean, not a single pixilation, and I have been in contact with Ken at BI-5 support trying to find the right protocol for these two cameras, and no luck! Foscam setting works the best!
7) and lastly, I have turned the "Hardware Accelerated Decode" to 'NO', instead of "Default"!