SM Dropping Connection

We have Advantage 2450 AP on which 3 SMs are connected.Of this
1 SM gets connected with RSSI of 1200 & jitter 1/3 with Spectrum very clear.

The SM on booting immediately gets connected.But after 2 / 3 minutes drop the connection & then it never comes up, unless we reboot the SM.

We upgraded to 7.0.7 recently.All APs & Other Sms r on 7.0.7

Is something t do with 7.0.7 firmware…?

Replaced the SM.Link is doing well.