Back-UPS Pro 900 Ethernet pass through problem

[BillP]

This question was originally posted by Magnus on APC forums on 7/31/2020

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Hi, I recently bought a APC Back-UPS pro and it's been working fine except for one major problem.

I'm running this in a home environment where I have computers situated in different rooms connected to an ethernet which is in turn connected via a router to the internet.

I have my Back-UPS to protect my NAS /application server from surges and power outages. In the same room as the server I have my computer lab and main office and a couple of Ethernet 1 Gbps switches. I have "isolated" this part of the home from surges by running the ethernet connection through the ethernet surge protection on the Back-UPS.

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For the most part this runs fine with my max internet speed 100 Mbps fiber. But suddenly the connectivity is cut off completely, this seems to be happening  quite frequently while browsing and downloading files. The weird part is that I have run OOKLA speed test, DSLreports and local speedtests with iperf etc and all shows full speed at all times but as soon as I start downloading something or sometimes when clicking a link in my browser it cuts off intermittently, it has a tendency to happen while halfway through a large file download, corrupting the downloaded file.

It has literally taken me days to isolate this problem to APC, I have tried switching all the ethernet cables and finally when i bypassed the APC the problem went away.

Am I using the ethernet surge protection the wrong way or should I suspect that I have received a faulty Back-UPS unit?

[BillP]

This reply was originally posted by Bill on APC forums on 8/3/2020

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Hi,

To be sure we are looking at the right specs please post the exact model number of the unit. You will find the model number on the bar code stick on the back or bottom the the UPS.

[BillP]

This reply was originally posted by Magnus on APC forums on 8/3/2020

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Thanks for your reply, here is the model number:

BR900G-GR

[jbrousseau_apc]

This was originally posted on APC forums on 8/4/2020

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Hello,

I just bought the APC Backup UPS pro 900 and I face exactly the same problem. I have the same configuration with the UPS between the router and the switch.

I lose regularly my Internet connection and the speed is globally lower. I expected higher quality for a product branded "Pro"...

[BillP · Accepted solution]

This reply was originally posted by Secret on APC forums on 8/4/2020

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Hello Magnus,

There are several factors which could effect signal loss in your configuration.

The first being insertion loss. A slight loss of dB signal will be observed anytime entering and exiting a network component. By reducing the number of connections where ever possible, reducing cable length and ensuring connectors and plugs are properly terminated you may be able to minimize this signal loss.

The second factor is signal attenuation.This can often be attributed to environmental factors, such as signal coupling through EMI/RFI, wire leakage and electrical currents. Some ways to mitigate attenuation is through the type of data cable material and shielding being used or by adding repeaters to boost the signal strength. 

Another factor is signal capacitance which is often caused by excessive cable distances or data cables being coiled instead of cut to length.

Capacitance also exists when entering and exiting the TVS Diodes used in the protection of the circuit. If these TVS Diodes are encountering any electrical disturbances on the circuit that they are unable to shut to ground, they will begin to become saturated. As the TVS diodes begin to saturate, their ability to transfer data diminishes causing slower data transfer speeds observable by the user. If allowed to continue, the TVS diodes will eventually reach the point of Avalanche, in which the signal is completely block as to not damage the circuit. When the TVS diode is removed from the circuit, the Avalanche diodes will eventually "drain" to the point in which they can begin to pass power again.

It is difficult to say exactly what is impacting your configuration, however I would recommend investigating to determine whether or not, one or more of the above mentioned conditions is present.

SecretSquirrel

[BillP]

This reply was originally posted by Magnus on APC forums on 8/4/2020

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Hi SecretSquirrel and thank you for your reply.

Those are definately valid and classic ethernet problems and I can not definately clear myself from suffering from those factors, however, the fact remains that by simply moving the cable from the IN on the APC UPS to the next following switch directly, eliminates the problem completely so unless the ethernet ports of the APC Back-UPS Pro 900 is more sensitive to these things by an order of several magnitudes compared to your regular consumer 1 Gbps ethernet switch it can't explain my problem.

Currently I don't have the APC UPS connected to my network at all and everything is 100% @ 100% of the time.

I have never encountered a switch that exhibits these problems so my guess is that this has to do with the surge protection feature built in to the Back-UPS so that is cuts the ethernet traffic.

Either way it's a bit disappointing not being able to use the ethernet surge protection.

[jbrousseau_apc]

This was originally posted on APC forums on 8/12/2020

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Hi SecretSquirrel and thank you for your reply,

I confirm that I have exactly the same problem with the same model. The Internet works for few days and then crashes.

When removing the UPS and connecting directly the router to the switch, everything works well.

(Internet -> Modem -> UPS -> Switch -> computer)

Isn't it possible that this model has problems with ethernet cables?

Thanks