NS_I_LIMIT_BANDWIDTH (0x400D0070): Why Windows Media limits your stream

1. The WMS Bandwidth Limiter Plugin is the culprit

What's actually happening here is that Windows Media Services (WMS) has a built-in bandwidth limiter plugin, and it's active. The message NS_I_LIMIT_BANDWIDTH (0x400D0070) is a warning — not an error — that the server administrator at network location %1 has set a maximum bandwidth limit of %2 bps. You'll see this most often when streaming high-bitrate content (like 1080p video at 8 Mbps or live event streams) over a managed network where the admin wants to prevent any single stream from hogging the pipe.

The real fix: Disable the WMS Bandwidth Limiter plugin on the server side. Here's how:

1. Open Windows Media Services Manager (Start > Administrative Tools > Windows Media Services).
2. Select your server (e.g., SERVER01) in the left pane.
3. Click the Plugins tab in the right pane.
4. Find WMS Bandwidth Limiter in the list. Right-click it and choose Disable.
5. Restart the WMS service: net stop wmserver && net start wmserver

The reason step 3 works is that once the plugin is disabled, WMS no longer enforces any hard cap per stream or per client. The warning message vanishes because the trigger for it — the plugin's limit — is gone.

If you're not the admin, you can't fix this yourself. You'll need to ask the network admin to either disable the plugin or raise the limit. The message tells you exactly which location set the cap (%1), so you can point to the right server.

2. Publishing point limits — the second most common cause

If the plugin isn't enabled, the limit might be set on the publishing point itself. Each publishing point in WMS has its own bandwidth throttling settings. This is common when an admin wants to limit a specific stream (like a training video) while leaving others untouched.

How to check and fix:

1. In Windows Media Services Manager, expand your server and find the publishing point that's triggering the warning (e.g., Sample_Broadcast).
2. Right-click it, select Properties.
3. Go to the Bandwidth tab.
4. Look at the Maximum bitrate setting. If it's set to a specific number (say 2000 Kbps), that's your cap.
5. Change it to Unlimited or raise it to a value higher than your stream's bitrate.
6. Click Apply, then restart the publishing point (stop/start it under the General tab).

The reason the limit is per-publishing-point rather than global is that WMS lets admins tune different streams for different audiences. A live event might get 4 Mbps while an archive video gets 1 Mbps. But if you're hitting this warning, your stream's bitrate exceeds that per-point cap.

3. Client-side bandwidth detection — not a real cause, but worth ruling out

Some people think this warning comes from the client (Windows Media Player) detecting network congestion. It doesn't. The NS_I_LIMIT_BANDWIDTH event is always server-originated. The client just reports what the server tells it.

However, I've seen cases where a proxy or firewall between the server and client modifies RTSP headers in a way that mimics a bandwidth limit. This is rare — maybe 1 in 100 reports — but worth checking if the server has no limit enabled and you're still seeing the warning.

Quick test: Temporarily bypass the proxy. If the warning disappears, the proxy is mangling your stream. Fix: update the proxy's RTSP inspection rules or add the server's IP to a bypass list. On a Cisco ASA, that means clearing inspect rtsp on the relevant policy or creating an ACL that exempts the WMS traffic.

Quick-reference summary table

One last thing: if you're a client user seeing this warning and you don't have admin access to the server, there's nothing you can do on your end. The bandwidth limit is enforced server-side, and no amount of tweaking your network settings or reinstalling Windows Media Player will change it. You'll need to contact the server admin and ask them to raise or remove the limit.