Disturbing interference between SXTsq 5 ac and wAP ac

I had seen this last year, but then the devices were just laying on a table. Now installing 10 SXTsq 5 ac as PtP with wAP ac and hAP ac2 as client connect.

The installation is on its proper place. SXTsq and wAp ac outdoor, hAP ac2 indoors. All working on different frequencies.

One of my PtMP connections was very unstable : SXT sa 5 to SXT sq 5 ac. 5540MHz/ 20MHzCe/ ETSI power limit 27dBm . Signal received -44 dBm

There is one wAP at 55 cm sideways from the SXTsq looking in the same direction. The wAP is operated at 5260MHz/20MHzCe/ETSI limited power 23 dDm.

The SXTsq sees that specific wAP at 5580MHz at signal strength -72dBm. That’s a delta of 320MHz. The SXTsq connections drops regulary (minutes, hours) . Scans for a new connection, there are 4 AP’s in the “wireless,debug” beacon list. All at different frequencies, the wAP is one of them at 5500MHz, with his correct SSID but wrong frequency. It is not seen at the set frequency.

Changed the wAP to 5180MHz (yes I know, it are indoor frequencies) , and same story , wAP now seen by the SXTsq at 5500MHz. Again a delta of 320 MHz and close to the needed 5540 MHz.

Lowered the power of the wAP. Does not disappear, is just lower. Would need to drop 24 dB to get it out of the way.

Greater distance would reduce the signal. 6 dBm with double distance, for -24 dBm that would need to be 8 meter !

This is not seen with the hAP ac2. Bad shielding of the wAP ac??? Unlucky placement? Probably, as when set at 5580MHz (and 10 minutes wait) the signal is impossible strong at the set frequency. (The SXTsq never catched or reported the indoor frequencies in the scan.)

Is something wrong with the frequency sidelobes in the wAP ac, or is the SXTsq antenna gain creating something when indoor frequencies (5180 till 5320) are received ???

Workaround: swapped the 2 devices, and due to their relative position the signal reception dropped by 20dB.
Outdoor freq still captured at -48dBm, but those 320MHz related sidelopes of indoor freqs are down to -92 dBm.

wAP ac is now on 5300MHz (sidelobe will be at 5620MHz) and power -6dBm compared to ETSI regulation (antenna gain method).
No sign of wAP20 in background scan with this setting. (Cannot use Snooper to check, as my connection is over this wlan1)