lost connection, not polled for too long

hello guys

I made a link between two points at 40 km, link goes down average every 30 minutes and log on I read the following message:
"lost connection, not polled for too long "
What does it mean?

Please give us more details about the link.

Signal Strength?
CCQ?
SNR?
Equipment?
Settings?

Hy

Tx/RX Signal Strength: -65/-65 dBm
Tx/Rx CCQ:95/91%
SNR: 53dB
Equipment RB: RB411AH FW Ver 5.0 Stable
Equipment Radio:Ubiquiti SR71-15
Setting: Band 5Ghz A
Frequency 5500Mhz
Tx/Rx Rate: 54Mbp/24Mbps
Wireless Protocoll:nstreme
Mode:Station
HT TxChains =chain0
HT RxChains =chain0