Unstable client connectivity

RouterOS General
1

i use RB433UAH as an AP and have clients using RB411. one moment the clients are connected, the next moment they lose connection. they are connected with a tx/rx signal strength of -78/80 and tx/rx rate of 36.0/24.0Mbps on average. i realised at times the tx/rx rate drops to 6.0/6.0Mbps.
AP routes and lists station wireless IPs in one moment and drops it in another moment.

i need help.

my email is kwadzo_tamakloe@yahoo.com

2

What protocol u use for connection?

What is the distance between AP and Client?

3

maximum client distance is 8km, OSPF routing protocol