Plex Buffering on NAS: How to Fix It

Many Plex buffering problems can be addressed without replacing the NAS, depending on whether the limiting factor is the network, playback settings, or transcoding performance. Enable direct play for supported clients, cap remote streaming quality to match your upload speed, and check your network for wireless interference or congestion. A Plex-compatible hardware-accelerated server can reduce transcoding-related buffering, but support depends on the NAS operating system, Plex version, codec, and playback configuration. Work through these fixes in order before concluding the hardware is the problem.

Why Plex Buffers on a NAS

Plex buffers when the server cannot deliver video data to your client fast enough. On a NAS, this breaks down into three causes: the NAS is transcoding a file it doesn't need to (and the CPU can't keep up), the network between your NAS and your device is too slow, or your internet upload speed is the bottleneck for remote streams. Each cause has a different fix. Which is why jumping straight to hardware is usually the wrong move.

Transcoding is the process of converting a video file from one format or resolution into another that your playback device can understand. Think of it as a live translator working in real time. Direct play is the opposite: the file plays exactly as stored, with no conversion needed. Direct play requires almost no CPU resources; transcoding can max out an entry-level NAS processor with a single 1080p stream. Eliminating unnecessary transcoding is almost always the first fix.

Fix 1: Enable Direct Play and Direct Stream

For the Plex Web App player, open Settings and select Quality; configure other Plex clients separately in each app's quality or video settings. Set local quality to "Original" or "Maximum" where the local network supports it, and set remote quality slightly below the server connection's measured upload speed. and ensure both "Allow Direct Play" and "Allow Direct Stream" are enabled. Direct play sends the file to your device unchanged; direct stream repackages compatible audio and video streams into a supported container, with audio transcoded separately when necessary. Both are far less demanding than transcoding. If your client supports the file format, Plex will use direct play automatically at these settings.

If your files are HEVC or AV1 and your playback device doesn't support them natively, Plex must transcode. HEVC Direct Play support varies by TV or streaming-device model, Plex app, container, profile, level, bitrate, audio, and subtitle format. older TVs and Fire TV Sticks without 4K support often cannot. The long-term solution here is either to have your content encoded in H.264 (universally compatible) or use a client with broader codec support like an Apple TV 4K or NVIDIA Shield.

Fix 2: Reduce Remote Streaming Quality

Remote buffering. Buffering when you're outside your home network. Is almost always caused by internet upload speed rather than NAS hardware. In the Plex app on your remote device, go to Settings, then Quality, and under Remote Streams set the quality to 4 Mbps or 8 Mbps. If the source requires more bandwidth than the selected remote-quality limit, Plex will generally transcode it to fit that limit. A standard NBN 50 plan delivers roughly 18-20 Mbps upload. Enough for one or two capped remote streams, but not for original-quality 4K.

Fix 3: Check Your Network

For local network buffering (streaming within your home), the most common cause is Wi-Fi interference or a weak wireless signal. A 2.4 GHz Wi-Fi connection in a congested apartment building shares spectrum with neighbours' networks and can drop below the bandwidth Plex needs mid-stream. Switch your streaming device to the 5 GHz band if available, or better yet, connect either your NAS or your streaming device (or both) to your router via Ethernet. A wired connection avoids Wi-Fi interference and commonly provides a 100 Mbps or gigabit link, but available throughput must still exceed the media's peak bandwidth requirement.

If wiring is not practical, a powerline adaptor or MoCA adaptor can carry Ethernet over existing power or coaxial cables in your home. Powerline and MoCA performance, reliability, compatibility, and price vary with the home's wiring or coax layout and the adapter model. For the NAS specifically. If your router is nearby. A single Ethernet run solves the NAS side permanently regardless of what your client device uses.

Fix 4: Check NAS CPU Load During Playback

If direct play is enabled but buffering continues on local streams, check the NAS CPU load while video is playing. In Synology DSM, open Resource Monitor. In QNAP QTS, open System Resource Monitor from the main menu. In Asustor ADM, open the Resource Monitor from System Preferences. Sustained high CPU usage suggests a processing bottleneck; use Plex Dashboard or Playback Info and the NAS process monitor to confirm whether Plex transcoding is responsible. Direct Play normally uses much less processing power than video transcoding, but there is no universal CPU-percentage threshold that confirms it.

High CPU during playback with direct play enabled usually means the format is genuinely unsupported by your client. High CPU even at idle (before Plex starts) suggests background services are competing for resources. Check whether any running apps. Download clients, backup jobs, surveillance station, or cloud sync. Are consuming CPU. Suspending them while streaming can restore headroom on entry-level NAS models with ARM processors and 2-4 GB RAM.

Fix 5: Close Background Apps and Services

NAS devices run multiple services simultaneously, and some background tasks compete directly with Plex for CPU and RAM. Scheduled backup tasks (particularly cloud sync or Time Machine backups) are common culprits. They often run at night but can overlap with evening streaming sessions. Anti-virus scans, thumbnail generation, and download clients all consume meaningful CPU on entry-level hardware. Reschedule these tasks to run between 2am and 6am when the NAS is otherwise idle.

Docker containers and virtual machines running on the same NAS compound the problem significantly. If your NAS runs Portainer, Home Assistant, or other containers, check their CPU and RAM consumption in the container manager. A single misbehaving container can consume enough RAM to trigger memory swapping, which degrades Plex performance even when the Plex process itself is not the bottleneck.

Fix 6: Upgrade to a NAS with Hardware Transcoding

If you have worked through fixes 1-5 and still experience buffering when the NAS must transcode (HEVC files, clients that don't support direct play, multiple simultaneous streams), the NAS hardware is the bottleneck. ARM-based NAS devices. QNAP TS-233, Asustor AS3302T, many Synology J-series and Value-series models. These ARM-based models lack Plex hardware acceleration and have limited software-transcoding capability, especially for high-resolution or high-bitrate sources. If stronger transcoding is required, use a specifically Plex-compatible hardware-accelerated NAS or run Plex Media Server on a separate compatible computer while retaining the NAS for storage.

Prices last verified: 7 June 2026. Always check retailer before purchasing.

Hardware transcoding requires a Plex Pass subscription, but once enabled it offloads video conversion from the main CPU to Intel's dedicated Quick Sync Video encoder. The Synology DS225+ contains an Intel Quick Sync-capable processor, but Plex hardware transcoding is not supported under its default DSM configuration. the QNAP TS-462 ($899) offers the same capability in a 4-bay form factor. For a deeper breakdown of models by tier and use case, see the Best NAS for Plex Australia guide.

Related reading: our NAS buyer's guide and our Synology vs QNAP comparison.

Use our free Plex Media Planner to check if your NAS can handle your library.

See also: our complete QNAP NAS Australia guide.

See also: our full Plex and Media guide.

Why does Plex buffer on a fast NAS with a good network?

The most common reason is transcoding. Even a fast NAS will buffer if it's converting video in software on a slow ARM CPU. Check the Playback Info while streaming to confirm whether Plex is transcoding or direct playing. If it's transcoding, investigate why: the client likely doesn't support the file format natively, or quality settings are forcing a lower bitrate than the original file.

Does Plex Pass fix buffering?

Plex Pass unlocks hardware transcoding on NAS models with Intel Quick Sync Video, which eliminates CPU-bound buffering on compatible hardware. It does not fix network-related buffering, NBN upload speed limits, or buffering caused by ARM processors that lack hardware transcoding support. On a specifically Plex-compatible NAS with supported GPU access, Plex Pass and enabled hardware acceleration can reduce transcoding-related buffering, subject to codec and playback limitations.

Plex is direct playing but still buffering. Why?

For a confirmed local Direct Play session, test network throughput first, then investigate the client, storage, and whether Plex is incorrectly treating the connection as remote. Check that your streaming device is on the 5 GHz Wi-Fi band or, better yet, wired via Ethernet. A Wi-Fi connection that looks like it has signal can still have low effective throughput due to interference or distance from the router. Run a speed test from your streaming device to confirm actual bandwidth. If the network checks out, check NAS disk health. A failing drive will throttle read speeds.

How much internet upload speed do I need for Plex remote access?

Required upload speed depends on the file's actual peak bandwidth, the client's buffer, selected transcode quality, and other simultaneous traffic; measure the server connection and leave headroom. Australian NBN 25 plans top out at around 5 Mbps upload, which is insufficient for most remote streaming. NBN 100/20 delivers 20 Mbps upload and handles one or two capped 1080p streams reliably. Choose a plan whose measured upload throughput comfortably exceeds the media's actual peak bandwidth requirement; the required NBN tier varies by file and connection technology.

Can I run Plex on an ARM NAS at all?

Yes, for direct-play libraries. ARM NAS devices (QNAP TS-233, Asustor AS3302T, many Synology entry models) serve Plex well when your clients support the file format natively. H.264 MKV files on a Fire TV 4K, for example, will direct play without issue. Problems arise when transcoding is needed: ARM NAS software-transcoding capability is model- and media-dependent and is generally limited compared with supported hardware-accelerated systems. For mixed-format libraries, choose a specific NAS model that Plex documents or verifies as supporting the required hardware-accelerated formats; an Intel CPU alone is not sufficient.

What is CGNAT and how does it cause Plex buffering?

CGNAT (Carrier-Grade NAT) is a configuration some Australian NBN providers use where multiple customers share the same public IP address. Under CGNAT, your router doesn't have a publicly accessible IP, so Plex cannot establish a direct connection to your server from outside your home. If Plex cannot establish a direct remote connection and Relay is enabled and supported by the client, it may use Plex Relay, where streams are limited to 2 Mbps. Contact your ISP to check if you're on CGNAT. Ask the ISP whether CGNAT can be disabled or a public IP supplied, and check whether a monthly fee applies.