Netflow services issues

I keep having to restart the netflow services on both of my pollers. For some I quit getting netflow data randomally. Any ideas?

Orion Platform 2015.1.0, SAM 6.2.0, QoE 2.0, IPAM 4.3, NPM 11.5, NTA 4.1.0, IVIM 2.0.0, VNQM 4.2