ePMP 4525 - Good signal/SNR bad performance?

[terintamel]

I have a simple test setup with on 4500L AP connected to one 4525 SM. Distance is around 400 ft with clear LOS.

As this is a test link I do not keep a close eye on it, but as I was upgrading from 5.6.1 to the latest 5.7.0beta I noticed that around April 13th the RX/TX rates of the SM dropped considerably. Where before I kept near DS MCS11 rates now the downlink is DS MCS8 or worse and uplink is around MSC9.

Radio RSSI is around -47db with SNR greater than 47db on both uplink and downlink.

Thinking it was interference I did a scan from SM and AP and could not find considerable change in noise. I then decided to try multiple frequencies from 5.7ghz all the way up to 5.9ghz and nothing was better or got close to the performance it was before.

I would think with almost 50db SNR I should see the pre-April 13th rates easily, but I cannot. What could be the issue?

[Fedor]

Could you please attach the screenshots of Monitor → Performance and Tools → eAlign pages?

Thanks you.

[terintamel]

Here it is. I think I might have an issue on the AP with one of the jumpers as now looking at the e-align page I have a pretty large chain imbalance. I’ll check the AP jumpers next chance I get and report back.

[terintamel]

It was a bad RPSMA jumper at the AP. Replaced it and the chains are even now with full MCS11.

@Fedor Could I suggest that Cambium add some type of warning to the SM GUI or AP GUI showing when a SM has a chain imbalance of 5db or more.