One trick that's worked for me is setting fixed hours with an actual timer - not just mentally, like "I'll finish at 6pm," but an actual alarm that goes off and forces you to shut everything down right then. In my case I realized that without that physical push I could barely disconnect, because your brain in remote work tends to procrastinate and then catch up in the evening. Beyond what everyone else says about physical separation, I'd add creating a "scientific closing ritual": it's not enough to just shut down your computer, but do something that marks the boundary, like changing clothes, stepping outside for even a quick walk, anything that's visible and repeatable every day. After a couple of weeks your body learns the pattern and when you do that action, your brain actually switches into "off mode."