Video Quality Issues Despite of Strong RSSI

Hello all! I just purchased a stick up cam (wired) and have a problem with the video quality: although the RSSI is pretty strong (-54 to -55), sometimes the videos are either choppy (but still sharp) or a bit pixelated (but not choppy). Most of the time the video quality is excellent though. It's interesting that the video quality is never changing during the recording or the playback of an event. That is, the video quality per event is always consistent. Some events have worse quality, some have better. Also, the issue seems to also affect photos it takes automatically when movement is being detected: some of the photos are perfectly sharp, others are pixelated. Any idea what this could be? I was thinking of a cloud problem or so. The Wifi connection is very stable and the router is close to the cam.