Couple of things going on that could impact your situation.
First, and you really don't want to hear this, the Roku 1 model 2710 was introduced in 2013 and discontinued in 2016. It's older tech, and has some age on it. Now, yes it is a supported device still, in that it gets updates and many app developers still support it, though some don't, and you'll find that to be the case more and more. It's possible the device is nearing end of life and if this is a recent development, this could be a symptom of that.
Next, the settings to control the bitrate on the device worked back in 2013 and before but not so much these days. The way the services stream has evolved over the years, and the things that worked a while back don't work so much any more. Adaptive streaming doesn't play nice with the old device settings. And those settings were never officially supported (they worked, but if they ever stopped, oh well; unsupported features have their drawbacks).
For Netflix, there is a profile setting on the Website where you can adjust the stream. It's not on the devices (Roku or other) but on the service. Not every service offers this. Some did and dropped it, others never did, some do offer the settings. But they are from the service, no generally within the app or on the device.
Roku Community Streaming Expert
Note: I am not a Roku employee.
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