@jp12321pj As you do not describe your configuration, it is difficult to make any suggestion about improving it.

  @yves_b Well, I'm a novice and haven't actually changed any settings in the Deco app, so I'm likely in default mode.

In an attempt to actually give some meaningful info, I grabbed some screenshots from the app. All the IP addresses share the same first 6 digital and then vary from there. The subsetmask was completely different from any other number string I saw in the app.

I hope this is enough to give me some tips and advice.

  @jp12321pj 

You apparently have 3 Decos, two of them in the same room.  Is that correct?
Could you share how your Deco are interconnected, and how the two devices of interest are connected to which Deco?

  @jp12321pj In this context, we use "backhaul" for the connection between the Deco.
How are your Deco interconnected?  The app shows that.
Similarly, the app shows, for each device, on which Deco it is connected.

Does it work better if the streaming device is connected to the Deco in next room?

To better understand, I would also test with the PS5 and the streaming device both connected to the main Deco, perhaps by unplugging the two satellite Deco.

  @yves_b besides the primary connecting to our modem, the other two nodes are wirelessly connected.

I tried the experiment of testing both the PS5 and streamer wirelessly (the PS5 is far from the primary Deco so can't wire it) to the single and primary node with the other two turned off and it worked well. But I also didn't have anything else consuming bandwidth, so not sure it if it represents how I'll actually use this.

The main use case is when other people are watching TV and I want to game at the same time, that's when bandwidth is being demanded by multiple devices. Im imagining some way to create / reserve / prioritize a direct line between the PS5 and streaming device, and then anything else on the network can get what's left over? Maybe this isn't actually possible and I'm making a lot of incorrect technical assumptions.

Any thoughts?

  @jp12321pj 

I expect that the traffic between PS5 and streamer does not go via Internet, remains local.  Hence I am surprised that you mention bandwidth issues.

In your regular setup (all Deco active, PS5 wired to the Deco in "next room"), when nobody is watching TV, does your streaming work well?

How are your Deco interconnected?  The app shows that.

There is a way to prioritise some devices.  This is intended to prioritise access to Internet, but it is worth trying.

First you activate "QOS" on the Deco app, and specify the bandwidth contracted with your ISP.
Then you can set some devices as "high priority".