The movie is on the NAS, you’re on the couch with the iPad – and then it stutters, stays black, or the app wants to download two gigabytes first. Yet streaming video from your own server is no rocket science: a player that understands WebDAV or SMB fetches the file piece by piece with range requests and plays while it loads. That’s called direct play, it needs no media server and no processing power on the NAS. It almost always fails in the same place: the format. This article shows what the iPhone plays out of the box, where you need Infuse, VLC or nPlayer, how streaming works away from home and on the TV – and why transcoding on the NAS is the wrong answer.
The short version
- MP4, MOV and M4V with H.264 or HEVC play natively on the iPhone, HDR included – every WebDAV player streams them without downloading.
- MKV, AVI, DTS and PGS subtitles are beyond iOS. For those you need Infuse, VLC or nPlayer – or you remux the video into MP4 once, without re-encoding.
- Transcoding on the NAS is over: Synology dropped video conversion with DSM 7.2.2; DS video now only streams what the device can play itself.
- Away from home: WebDAV over HTTPS on port 443 or 5006, no QuickConnect, no open SMB port. Or a VPN.
- On the TV: via AirPlay and Chromecast – WebDAV Browser fetches the video with your credentials and relays it; Infuse can do that only with Pro.
At a glance: which player for which collection
Your own recordings, Handbrake exports, purchased movies in MP4 or MOV
Streams with range requests, with SRT subtitles, Picture in Picture, resume, AirPlay and Chromecast. One server free, no data collected.
A big movie library with MKV, HEVC, Dolby Vision and DTS
Infuse
Plays practically everything and fetches artwork and metadata. AirPlay, Google Cast and cloud streaming only come with Pro ($16.99 a year or $99.99 once).
Play everything, pay nothing, home network only
VLC
Free, open source, MKV and DTS included, SMB, NFS and SFTP as sources. VLC doesn’t advertise WebDAV on iOS.
MKV over WebDAV for little money
nPlayer
$4.99 once, WebDAV, SMB and NFS, Chromecast, no data collected. Last update February 2025 – at your own risk with new iOS versions.
Plex or Jellyfin is already running anyway
Plex or Jellyfin app
Transcodes on the server when needed – which requires CPU or a GPU in the NAS. Not a good idea for a two-bay NAS without a hardware encoder.
Direct play, transcoding, download: three routes
Direct play means: the player on the iPhone fetches the file exactly as it sits on the NAS and decodes it itself. To do that it requests only the chunk it needs right now via HTTP range requests; seeking jumps within the stream. The NAS only serves bytes – every Storage Box, every two-bay enclosure can do that. Requirement: the device can handle the format.
Transcoding means: a media server such as Plex, Jellyfin, Emby or, formerly, Synology’s Video Station converts the video on the NAS into a format the client understands, live. That needs processing power, for 4K or HEVC a GPU or hardware encoder – and most NAS boxes don’t have one. Synology drew the conclusion: with DSM 7.2.2 video conversion is gone, Video Station no longer exists, DS video only plays what the device supports natively (Synology community on the end of conversion). For you that means: on a Synology NAS there’s no more transcoding without third-party software. The better news: you don’t need it if the format is right.
Download is the fallback: load everything, then play. Sensible for a flight, useless as a daily routine.
What the iPhone plays natively
Apple’s video stack – the same one in the Files app, in Safari, in every app that uses AVPlayer – is picky about the container and generous with the codec:
| Format | iOS nativeAVPlayer: Files app, WebDAV Browser, Safari | InfuseFirecore | VLCVideoLAN | nPlayerNewin |
|---|---|---|---|---|
| MP4, M4V, MOV | yes | yes | yes | yes |
| MKV | nocontainer isn’t demuxed | yes | yes | yes |
| AVI, WMV, FLV, TS | no | yes | yes | yes |
| H.264 | yes | yes | yes | yes |
| HEVC (H.265), including 10-bit and HDR | yes | yes | yes | yes |
| Dolby Vision | partlyin MP4/MOV, same profiles as Apple TV | yes | not verified | not verified |
| AV1 | partlyin MP4 from iPhone 15 Pro on | not verified | yes | not verified |
| AAC, Dolby Digital (AC-3, E-AC-3) | yes | yes | yes | yes |
| DTS, TrueHD | no | partlyDTS; lossless audio only with Pro | yes | partlyDTS only in nPlayer Plus |
| Subtitles as an SRT file | partlyonly with an app overlay, e.g. WebDAV Browser | yes | yes | yes |
| Embedded subtitles (PGS, ASS) | no | yes | yes | yes |
| Picture in Picture | yes | yes | partlynot consistent per reviews | yes |
Legend:yespartlynonot verified
iOS codec support per Apple’s AVFoundation and HEVC/Dolby Vision playback documentation; player claims from the vendors’ pages, as of November 7, 2026.
The rule of thumb: what comes out of the iPhone, Final Cut, Handbrake with an MP4 preset or the iTunes Store plays natively. What comes from the torrent world, Blu-ray rips or MakeMKV sits in MKV with DTS and PGS – and needs Infuse, VLC or nPlayer.
Top tip
MKV is just a container. If it holds H.264 or HEVC with AAC or AC-3, you don’t need to re-encode anything, only repackage – on the Mac in seconds, without quality loss: ffmpeg -i movie.mkv -c copy -c:s mov_text movie.mp4. After that the file plays in every Apple player, streams via AirPlay to Apple TV and needs no special player. Only DTS audio has to be converted to AC-3 once (-c:a ac3); PGS subtitles are left out.
Which protocol for streaming
The second stumbling block is the path between NAS and iPhone:
| Protocol | Streaming at home | Away from home | Files app | Typical apps |
|---|---|---|---|---|
| SMB | good; range access through the file system | VPN only – port 445 doesn’t belong on the internet | yes, mountable as a server | Files app, VLC, Infuse, FileBrowser |
| WebDAV over HTTPS | good; range requests are part of HTTP | yes, over port 443 or the NAS port, encrypted | no | WebDAV Browser, Infuse, nPlayer, WebDAV Nav+ |
| DLNA / UPnP | okay, but no seeking with many servers | no, multicast on the home network only | no | VLC, Infuse |
| Plex / Jellyfin / Emby | good, with transcoding when needed | yes, through the server | no | their own apps |
For the home network, SMB is fine – the Files app can even do it itself, and VLC or Infuse play straight from it. Away from home, WebDAV over HTTPS remains the cleanest route: it runs over a port every firewall allows, the connection is encrypted, and range requests are built into the protocol. On Synology you need the “WebDAV Server” package with HTTPS on port 5006 and a DDNS name with port forwarding – QuickConnect doesn’t carry WebDAV, as we explain in the guide to WebDAV on iPhone and iPad. The alternative is a VPN into your home network, after which you can use SMB again.
A word on data: a 90-minute movie in 1080p HEVC runs four to eight gigabytes. Streaming loads exactly what you watch – so the whole movie if you watch all of it. For the train, offline copies made on Wi-Fi are the better choice.
On the TV: AirPlay and Chromecast
This is where it gets technically interesting, because an Apple TV or Chromecast doesn’t get the video from the iPhone but has to fetch it from the server itself – and of course the TV shouldn’t know the NAS password. WebDAV Browser solves that with a relay on the device: the iPhone fetches the video from the server with your credentials and serves it to the TV under a one-time address with a random token. Credentials never leave the device, the address is valid only for that TV and only while the player is open. Three rules:
- Same Wi-Fi. iPhone and TV have to see each other. Guest Wi-Fi with client isolation and cellular-only connections don’t work.
- Formats stay formats. An Apple TV plays MP4 and MOV with H.264 or HEVC via AirPlay; a Chromecast additionally plays WebM. MKV fails on the TV just as it does on the iPhone.
- Subtitles. Via Chromecast, SRT subtitles reach the TV as WebVTT; via AirPlay, the Apple TV doesn’t show the iPhone’s overlay.
Infuse can do AirPlay and Google Cast as well – but only with Pro. VLC streams via Chromecast, nPlayer too; AirPlay video isn’t documented for either.
WebDAV Browser: streaming from the first server connection
We didn’t build WebDAV Browser as a player but as a client for everything on the server – with a player that gets the streaming cases right:
- Range requests instead of downloads. Videos start immediately, seeking jumps within the stream, resume remembers where you were. If a server doesn’t support streaming, the app can download the file.
- SRT subtitles from the same folder, toggled with a button; Picture in Picture, background audio when locking.
- AirPlay and Chromecast with the relay described above – your credentials stay on the device.
- Offline copies for the flight, on the iPhone also usable as a cast source without a server.
- Certificates. Self-signed NAS certificates are remembered on first connect; streaming works as soon as the certificate is pinned.
- One server free, streaming, AirPlay, Chromecast and gallery included. No data collected, passwords only in Keychain.
The limit is Apple’s video stack: no MKV, no AVI, no DTS – for such files the app offers “Download and share” to hand them to Infuse or VLC. If you have an MKV collection, you’re better off with Infuse or you remux the files once. For everything that’s MP4 or MOV, you don’t need a second app.
How to set up streaming from your NAS
Check the formats
Look at the file extensions in your collection. MP4, M4V and MOV play in every Apple player. For MKV, AVI or DTS audio you decide: install Infuse or VLC, or remux the files to MP4 once with ffmpeg, without re-encoding.
Enable WebDAV with HTTPS on the NAS
Synology: “WebDAV Server” package, HTTPS on port 5006, ideally with a Let’s Encrypt certificate from DSM. QNAP: WebDAV under “File Services”. Nextcloud and the Hetzner Storage Box speak WebDAV out of the box.
Connect the player on your home network
Enter server address, user and password, run the connection test. With a self-signed certificate the app has to remember it deliberately. Open a video: if it starts within two seconds and seeks, direct play is working.
Set up access from away
Create a DDNS name, forward only the HTTPS port of the WebDAV service, never HTTP or SMB. Alternatively a VPN on the router or NAS. Then test the connection once on cellular.
Add the TV
Put iPhone and Apple TV or Chromecast on the same Wi-Fi, start a video, tap the AirPlay or cast button in the player. Check once whether subtitles arrive – via Chromecast yes, via AirPlay no.
Frequently asked questions
Why does video from my NAS stutter on the iPhone?
Usually for one of three reasons: the device can’t play the format natively and the player decodes in software (typical for 4K HEVC in MKV on older devices), the connection can’t keep up with the bitrate (edge of Wi-Fi, cellular), or the server doesn’t support range requests and the app has to load the whole file. An H.264 MP4 over WebDAV on your home network practically never stutters.
Does my NAS need transcoding to stream videos to the iPhone?
No, as long as the format matches the device. Direct play over WebDAV or SMB delivers the file unchanged, and the iPhone decodes it itself. You only need transcoding for formats that neither the device nor a player like Infuse can play – or to lower the bitrate for slow connections. Synology dropped its own video conversion with DSM 7.2.2 anyway.
Can the Files app play videos from my NAS?
Yes, if the NAS is connected over SMB and the video is MP4, M4V or MOV. The Files app then streams with the system player. Over WebDAV it doesn’t work because the Files app doesn’t support WebDAV; MKV and AVI it never plays.
How do I play MKV files from my NAS on the iPhone?
With Infuse, VLC or nPlayer, which bring their own decoders. Or you remux the files into MP4 once without re-encoding, if they contain H.264 or HEVC with AAC or AC-3; after that they play everywhere, AirPlay included. DTS audio has to be converted to AC-3 in the process.
Can I stream videos from my NAS when I’m away?
Yes, over WebDAV with HTTPS and a DDNS name, or over a VPN into your home network. Synology’s QuickConnect doesn’t carry WebDAV. Keep data usage in mind: a 1080p movie in HEVC loads four to eight gigabytes. For train rides, offline copies made on Wi-Fi are the better choice.
Do subtitles reach the TV when streaming?
Via Chromecast yes: SRT files go to the TV as WebVTT. Via AirPlay the Apple TV doesn’t show the iPhone’s subtitle overlay; there only embedded subtitles in the MP4 file (mov_text) help, which you create when remuxing with ffmpeg.