MikroTik

Hi guys, I've 2 RB433AH, one is client, other is AP, running at 5GHz.
I got stable wireless link: SNR 27dB and CCQ 96/98% at 6MB.
My RB have both ethernet and wlan in same bridge, with IP address assigned to erhernet port.
I can see link up, but often I can't ping client and I can't reach devices connected to client's ethernet port: 30-40 seconds of ping with timeout result, then 20-40 seconds I can ping at 2ms, then timeout again.....
Is there a way to debug this trouble?
Thabks.

Is the channel width correctly set in the properties of both radio's? For example 20 MHz?

And can other devices connect to the AP? For example, mobile phone, or laptop? So they have good and stable internet?

Of course wireless settings are correct, or I won't get link at all.
I have had link up for months before this trouble.
I'm not using other devices to connecto to the AP, just remote radio.

You can try setting
-HW. Protection mode to CTS-to-self and HW Protection Threshold to 256 on both sides.
-Also set Adaptive Noise Immunity to ap-and-client.
-And lowering tx power.

Maybe there is a neighbour with same or close channel s you. use SSID'er to have a look. Also, there might be a different interferer, like a wireless camera (NON WiFi, but propriety protocol which cannot be seen by the PC).