Unless we can safely change iFrame interval and/or frame rate in the AD110, I think we are stuck with the lag with STREAM enabled. It’s a complicated dance in how Stream works that I can’t explain other than to refer comments made by the head developer of Stream.
You may find this post interesting as it contains a detailed review of several different camera integrations with, and without stream enabled. Also note the reply from the developer, hunterjm.
BTW - we do know that it is possible to modify AD110 video configurations via the API, but one guy who tried it confirmed it worked, but then his AD110 died shortly after. It could have been due to overheating the CPU with the different settings, or it could have been coincidental.
Coming in the next .115 update are significant improvements to Stream (such as adding audio). I did not see in the PR’s anything related to lag improvements though.
EDIT (12/2021) - An important improvement to STREAM was the addition of a new “LL-HLS” Low Latency option. I’ve added it to my stream config and it works! Now, I am only seeing about 2.5 seconds of lag on both ethernet cameras and Wi-Fi doorbell. I can live with that.