I have Intel NUC (i7 8559U) for Jellyfin server and 1gig connection. No shuttering issue in my home network, it run flawless in HTML5 Player, Jellyfin's ExoPlayer and MX Player Pro.

Likely the issue is the transcoding process, you would need look into that. It could be the CPU is not transcoding quickly enough, I/O bandwidth issue (CPU to hard drive or vice versa), QuickSync are not enabled in Intel CPU. Newer video codecs (HEVC/AV1), audio codecs, 10-bit, higher resolutions are a big factor in transcoding.