I have two RB435G with Mikrotik Wireless cards at 7km.
5GHz-only-N
20/40Mhz HT Below

The link used to be fine when first installed.
Tx/Rx Signal -49/-49
Tx/Rx CCQ 98/99
Tx/Rx Rate 150.0Mbps/150.0Mbps

I happened to notice on the slave side today
Tx/Rx Signal -49/-49
Tx/Rx CCQ 6/91
Tx/Rx Rate 6.5Mbps/121.5Mbps

So I thought of interference but changing frequencies only effected the RX. (Made it worse)
Also upgraded to latest software and firmware.
The only time I can get it to go higher is to run bandwidth test between the two radios.
Then the Tx CCQ goes to around 44 and the Tx connect rate goes to 60.0Mbps but never any higher.
The Rx CCQ goes to 99 and Rx rate goes to 150.0Mbps

Speed test was Tx 60M and Rx 113M
Has any one else seen this and how to fix it?

Thanks for any help
Arthur

Are there very close to your antenna any other antennas too?

Yes on both sides

Mmmmm.........That's your problem.
Now you have 3 options.

1. You must use Bandpass filters for you frequency,
2. Give a space between your radio at least 2m (minimum) away from the other antennas.
3. Use a dish shield (if you have a dish antenna) and also move it away from the other antennas.