Port 554 Blocked?

[#1]

I have some security cameras that use RTSP and I'm able to view these fine on the internal network. When connecting remotely, however, the feeds show very briefly but then the entire Plusnet connection disconnects. 

Is port 554 being filtered perhaps and is there any way to resolve? This is not high bandwidth usage and only for very brief interactions when people ring the doorbell etc. It happens without fail when remotely connected. You can see the outages in the below chart from my Unifi router.

[#2]

@AndyMillne what is the resolution, framerate and compression algorithm of your camera ?

What broadband product do you have and what is your upstream speed ?

I'm thinking that the RTSP from the camera is maybe saturating the upstream bandwidth and thus the PPP 'keep alive' packets are getting lost/delayed and so the PPP times out and disconnects

[#3]

Thanks @MisterW hmm that sounds plausible. The resolution is 2k and our Plusnet connection is somewhat limited in terms of bandwidth. The issue was probably masked on our 100mbit Virgin Media upload. We've gone back to a FTTC connection however with Plusnet as I would rather support good customer service and make do with a slower connection until FTTP via Plusnet is available.

I'll expose the low res streams on the cameras (640 x 480) and try with that to see if it makes any difference.

[#4]

@AndyMillne The issue was probably masked on our 100mbit Virgin Media upload

Almost certainly!.

There's a bandwidth calculator here https://www.cctvcalculator.net/en/calculations/bandwidth-calculator

I'd aim for a bandwidth usage of no more than around 70% of your upstream speed if possible. 

[#5]

It would help to confirm @MisterW 's theory by inspecting the router log at the observed disconnection times.

If they show only the loss of PPP then that would match the theory, however if it also shows a loss of xDSL there might be other things to consider.

[#6]

@Townman 

I think this is typical Hub-2 bufferbloat, where excessive upload bandwidth utilisation causes ALL traffic on the connection to stall (while the offending traffic persists), giving the 'appearance' that "the entire Plusnet connection disconnects".

Looking at the image provided, when the ping plot along the bottom of the picture goes red, the top graph is showing peaks in (assumed to be) upload data transfer,  so I'm not convinced that either the PPP or VDSL is dropping because you'd see gaps in the traffic if the connection was actually failing.

@AndyMillne  do you happen to own any other broadband routers from previous ISPs ? (with a VDSL or ethernet WAN port)

@AndyMillne

Could you run the following test to give us an idea of how your line and router are behaving -

https://www.waveform.com/tools/bufferbloat 

then under the results find "Share Your Results:",   hit the  [Copy]  button,  and paste that URL back in your forum reply.

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[#7]

Thanks, I'll run these tests later when I'm back on that connection.

I'm using the Hub2 in bridge mode with a Unifi Dream machine Pro. In terms of other ISP routers, I don't have anything ISP but do have an original Openreach modem I could use in place of the hub2 if it's likely to make a difference.

The Plusnet connection is not giving me the minimum guaranteed speed as it should be approx 52/7. A call to support and they told me the data on signup was wrong and the actual guarantee should have been low 40s/4 ish and I could get out of the contract at any time if I wanted to but I would rather stay with a slower connection than go back to Virgin. I'm hoping FTTP will be available in the next 12 months or so.

I'll run those tests though later and report back. The reason I think the entire connection is down is because I can't connect to the Unifi control panel from outside the home when it happens and nothing else inside the home works for internet access.

[#8]

@AndyMillne 

Unifi Dream machine Pro.

Well that certainly has QoS facilities. So you could set it to limit the upstream bandwidth available to the camera.

[#9]

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@AndyMillne wrote:

I'm using the Hub2 in bridge mode ... but do have an original Openreach modem ... if it's likely to make a difference.

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Stick with the bridged Hub-2 for now.

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@AndyMillne wrote:

I'm using ... a Unifi Dream machine Pro.

After you've run the baseline bufferbloat test and posted the results here,

try configuring the UDMs "Smart Queue" or any other available QoS features to manage your limited upload bandwidth,

then try to get your bufferbloat score to say "C" (which would be a good starting point given your upload speed of 4Mbps)

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[#10]

Thanks again all. I've enabled low res streams which alone resolved the issue in that the streams are now viewable and everything doesn't lock up. I then performed the buffer bloat tests before and after enabling smart queue with values set to downrate 46mbps update 7mbps.

Before (F): https://www.waveform.com/tools/bufferbloat?test-id=861bd618-c5bd-4b8b-a0b3-04cd1de0a21c

After (A): https://www.waveform.com/tools/bufferbloat?test-id=8da350c2-303e-4ff0-8d49-4b3771a75aea

Adding a reminder to my calendar for Openreach's end of 2026 to disable the smart queue

[#11]

Wow, well done that's a great improvement !

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@AndyMillne wrote:

Adding a reminder to my calendar for Openreach's end of 2026 to disable the smart queue

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If you choose an FTTP package up to 300Mbps, other people here have seen that it's still worth using QoS.

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