Intermittent connectivity issues

Good afternoon all,

I'm not sure what to make of this one so hopefully someone here can offer some advice.  I have a backhaul link that is pretty solid and sittng at about 14 miles, during the day and most nigths holding a steady RSSI around 68-70 and throughput of around 30-50mb.  It used to be occasionally and recently more often, but in the evening anywhere from 6pm to 2am my connection just goes south.  The connection RSSI jumps to 82-85 dropping connections, MCS around 1 and throughput of less than 2mb.  Then all of the sudden everything goes back to normal.  It's not traffic because I can consistently hold a solid test for 20 minutes and the connection holds steady.  I wouldn't think its interference because I can do frequency scans and edetect and everything looks good.  I don't think it's detecting anything else in the area. 
I can't do a frequency scan from the remote location, but the edetect looks fine from that location. 

What I've tried thus far:

  • Changed frequencies while this is happening and they are all bad, not matter what frequency I try I can't get a connection of better then 80 RSSI.
  • I wouldn't think it was antenna alignment since during the day it seems fine.  I wouldn't think it would move and then move back later.
  • Tried different modes, but they all seem to react the same.

I've attached some screen shots of the connection so maybe you can see something I'm not.

Thanks in advance,


1 Like

Hi.  Where are you located?  I'm wondering if it's an 'atmospheric duct' due to humitidy or temerature?  We have a long link that does a similar thing, and we see it most often when it's been frosty and then it warms to thaw. As the humidity comes out of the trees, the link drops off quite a bit.

So for us, if the temps are  below about -4c (lower than about 25 F) or if they are higher than +4c (about 40 F) things are fine.  But between the two, right when it's hovering around freezing/thawing - that's when we have issues on that link.


Really?  I wouldn't have thought of that but we are along the gulf coast so temperature shouldn't be an issue.  We stay around 70 most of the time this time of year.

I haven't noticed any foggy nights lately, but I have noticed that sometimes that makes a difference across all of our links.  It is random so I'll have to look at a couple of other links and see if they are any slight differences with them also.  I have only been concentrating on the one that keeps dropping off, but that's a thought.



I love on the gulf coast and thermal fade has been pretty bad over the past few weeks. Some of my links at -59 are fading to -80's or completly away.

Wow really?  What is the cause of that, the humidity or is it the salt in the air?

Are there any workarounds or frequencies that work better than others in this scenario?

I'll have to monitor our other backhauls and see if they are doing the same thing, this is the only one that I notice that drops the connection.

The next longest one I have is about 12 miles and its shooting straight across the coastline.

I wonder if its latency or something could be adjusted from the AP side.


On a side note, where are you located?

Normally it happens for me when theres a sudden change in temperature. It's usually worst for me when its -70ish during the day then drops to -50 within 2 hours after the sun goes down. I think it's also dependant on the elevation - I have ospf running with two different routes to my main tower. One dish is at 90ft, while the other is a 60ft. They almost never fade at the same time so generally the network can accomidate for links fading away.

I've recently heard using 45 degree slant feedhorns will help with this, i've ordered some to test next week.

I'm south of houstion, but north of corpus christi and I'm right on the coast.

I could be wrong on all these assumptions, but it's what i've experienced so far.