Very possible it's getting ready to keel over. The Roku 3 4200 was first released in March 2013, than a second version (same name, model 4230) was released in April 2015. Even if you haven't had it that long, that's how old the design is. The Roku 3, especially the second version, was one of the best players they ever made, but electronic devices can fail with age. If you still need a wired network connection, the Ultra is the only current player that has it. Most of the larger Roku TVs also have wired. If you are OK with wireless, the Premiere + (3921) is the closest match to your Roku 3, but far more capable. It includes 4K/HDR support, as well as MPEG-2 video support and much more powerful.
Nvidia Shield, Roku Stick (3600), Ultra (4640), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.