Since it’s a custom non-standard rip, some media players might choke on the unusual resolution. Subtitles (crucial for Dothraki/Valyrian scenes) may be hardcoded poorly or missing.
It’s important to be upfront: . Official versions are 1080p, 4K, or at worst 720p. “406p” is a non-standard, likely custom resolution—probably the result of an overly compressed encode intended to save file space at the cost of visual quality. Game Of Thrones Complete Season 1-2-3-4-5 406p Mkv
The only upside. A complete 1–5 season set at 406p likely fits on a small USB drive (maybe 20–30GB total, vs. 200GB+ for 1080p). Fine if you’re watching on a tiny phone screen during a commute and have zero other options. Since it’s a custom non-standard rip, some media