Buffering is almost never caused by the app itself. In nine cases out of ten it comes down to one of three things: the connection between your router and your device, congestion on your home network, or a picture quality setting that is higher than your bandwidth can carry.
The first thing worth checking is how your device reaches the internet. Wi-Fi is convenient but loses a lot of speed through walls and floors. If your television sits near the router, a network cable will usually fix stuttering outright.
Next, look at what else is running. A large download, a game console updating in the background or several phones streaming at once will all compete for the same bandwidth. Pausing the download often solves the problem instantly.
Finally, check the quality setting inside the app. Meridian adapts automatically, but if you have pinned the quality to 4K on a connection that cannot sustain it, the picture will stall. Setting it back to Auto lets the stream adjust itself second by second.