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cliffordjames
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RB951Ui-2HnD PoE out failure.

Tue Aug 07, 2018 1:44 pm

I work for a small WISP in the UK. We use the RB951Ui-2HnD as the primary router we give customers. This model has the single PoE out on port 5. We started using this port to power the Ubiquiti NanoBeam M5's we use for the CPE side of our wireless links. We have had a consistent failure when doing so. One of two things happen, either the plug on the power supply blows with a puff of smoke or the router simply stops providing the power while otherwise continuing to work. We've switched back to using PoE injectors to power the external device and have had no issue with the router or it's plug either way.

My questions is whether they are designed so they should be able to handle this arrangement just fine. If so whether we could be doing something to cause the issue or if we are being provided with a power supply that isn't fit for purpose. I doubt the latter as the specs on the plugs check out and they seem to be standard UK model plugs designed for the kit.

Let me know if you need any further details. I can provide pictures of equipment and setups if that helps. If the router is simply not designed for that purpose that's fine. Really just trying to figure out if we need to reach out to the supplier to complain and let them know about the issue OR if we need to change our setup in some way.
 
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Re: RB951Ui-2HnD PoE out failure.

Tue Aug 07, 2018 6:54 pm

From another WISP in the UK. We too are seeing this problem. More often than not PoE disappears, a reboot does not fix it but a prolonged power off (1hr) does.
We don't want to switch back to injectors either we have seen a sharp rise in routers going "duff" and dropping power out of P5.
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cliffordjames
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Re: RB951Ui-2HnD PoE out failure.

Tue Aug 07, 2018 8:32 pm

We've had a few customers who had left it offline for longer periods of time and seen it come back as well but we hadn't tested that as a potential fix. Not that our customers would really like that solution but it might work for those folks I can't get out to right away. Thanks for the reply. Glad it's not just us.
 
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Re: RB951Ui-2HnD PoE out failure.

Thu Sep 20, 2018 4:21 am

I was thinking about it. The declared max power usage of the Ubiquiti is 8W. At 24V that would be 0,3333 A. Inside the 500 mA limit allowed by the RB951Ui-2HnD, but not so much. But the network cable would run to the roof, where the Ubiquiti is. Longer lengths, lower voltage. Lower voltage... more Amperes.

All the problems look current problems to me. Blowing PSUs, PoE port not providing current, router works again after period of cooling of... Have you tried a test setup, connected to a more robust PoE power source? The CSS106-1G-4P-1S can take a load of on amp.
 
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Re: RB951Ui-2HnD PoE out failure.

Sat Feb 16, 2019 2:06 pm

Have had the same issue, doesn't matter on cable length. 1m or 20m, it'll all fail eventually.

Not limited to the 951 as well. RB3011s and RB2011s have failed as well.

Hell, I came looking if others had the issue because my RB2011 decided it can't power my cap lite (166ma 20m cat6) anymore.
 
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Re: RB951Ui-2HnD PoE out failure.

Thu May 02, 2019 11:45 am

hi all

Noticed this thread and have had a few 951's do exactly the same thing recently. the PoE just stops working, the RED LED goes out and nothing brings it back. the router otherwise is working fine.

These have all been feeding ~3 watt loads and is proving costly. Perhaps we should dump MT wifi routers here as this is proving more expensive with reputation damage and unnecessary site visits.

Did anybody ever come up with a solution to this that works without replacing it?

thanks

Bill

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