Seemingly Impossible Network Problem Involving EA1 and BenQ Projector

[SHPRemote]

I’m having a truly weird networking issue that seems to involve my EA1 and my BenQ LK990 projector.  

In my home I have a EA5 as my main controller.  It lives in my network rack in the networking room (the laundry room).  I have a UniFi USG, six UniFi switches and five UniFi Aps. The EA1 is located in an AV cabinet in my media room.  It is connected to an 8-port UniFi switch which is then connected to my primary 16 port POE switch in the network rack. 

The primary purpose of the EA1 is to provide C4 control of my BenQ projector.  To accomplish this, I have Chowmain’s BenQ Universal Projector Driver installed.  I have a C4 3.5 mm-to-DB9 Serial Cable plugged into Serial Port 1 of the EA1.  Because I had a spare Cat5e cable running from the AV cabinet through the walls and ceiling to the projector, I’m using that cable with Cat5 to Serial converters on both ends. Ari helped me set all of this up and it has worked perfectly until recently.

I was gone for a week and when I returned home, I noticed that I could no longer control the BenQ projector with C4.  I tried rebooting the EA1, but no joy.  Further, although my UniFi controller was showing that the EA1 was connected to the network, the C4 Composer HE said it was "offline".  At the same time, I noticed that my network performance at the AV cabinet switch (where the EA1 is connected) and downstream from there went to hell.  I have gig service and normally a computer connected by ethernet to this segment of the network will do 500+ mbps each way.  I was now getting between 1 and maybe 6 mbps.

I was trouble-shooting the issue and found that if I moved the EA1 to my network rack in my networking room, it would boot and show up on the network and appear online in Composer and my network performance went back to normal.  I could not test the serial control of the BenQ in that setup because there’s no cable in that room.  When I moved the EA1 back to AV cabinet and plugged the serial cable back in, everything went to hell again.  On a lark, I disconnected the serial cable from the EA1 and my network performance immediately jumped from 1 or 2 mbps back up to 500+.  I did this A/B test (serial cable in/serial cable out) many times and every time it was the same:  Plugged in—terrible network performance.  Unplugged—normal network performance.  Naturally I thought maybe the Cat5e cable running between the EA1 and BenQ was screwed up.  So, I tested it with a brand new cable (one that isn’t running behind the walls) but it was exactly the same. 

Here is where it gets really insane.  This problem exists whether or not the EA1 is physically connected to the UniFi switch!  IOW: Even if I disconnect the ethernet cable between the EA1 and AV cabinet switch, I have the same terrible network performance if the serial cable is connected.  As soon as I unplug the serial cable the network performance returns to normal. 

I just cannot begin to understand how this could be happening.  Ari has confirmed that my EA1 is not on WiFi.  The BenQ projector has no WiF and has no other connections apart from a 12v trigger to my screen and an HDMI cable running to my Marantz AVR in the cabinet.  (And, yes, just to be sure I disconnected both of those, but the problem persists.)

It seem like it must be an IP address conflict or something, but I still don’t understand how the EA1 or BenQ could be causing an issue if they aren't even connected to my network.  

Can anybody shed any light on this? 

 

 

[Cyknight]

1 hour ago, SHPRemote said:

but I still don’t understand how the EA1 or BenQ could be causing an issue if they aren't even connected to my network.

Any chance the EA1 is running ZigBee? Any chance there's an access point in that AV cabinet at the same time?

-Serial connection (for whatever reason) is crashing the EA1

-EA1 then starts spamming the zigbee connection setup

-which in turns drives the AP down, which is actually causing the network drop

 

This is crazy yes, but it would be the one possible connection if you've ensured the EA isn't trying to default to WiFi

[SHPRemote]

Hmm.  These are good ideas.  But I don’t have either ZigBee or Z-wave configured on the EA1.  There’s not an AP in the cabinet; the closest one is about 40 feet away.  I do have Vera in the cabinet with the EA1.  But I confirmed that its WiFi and Zigbee radios are both off.

I’m going to try a few more things to try to isolate the issue.  I’ll unplug (and power down) everything connected to the AV cabinet switch and the downstream switch.  Maybe that will give me some clues.

Like you, my first thought when the problem persisted even after I had disconnected the EA1 from the switch was that it must be a WiFi issue.  But I certainly don’t see the EA1 on the network as a wifi device.  

Thanks for helping!

[tekki70]

2 thing to really check, one would be make sure your not feeding a switch twice, could cause a loop, 2nd thing i would do is disconnect any lan to a tv as ive seen nic cards go bad in tvs and wreak havoc on a network, especially older frame tvs and some 32" older samsung tvs