By default, no traffic will be prioritized. When you configure QoS (as per the config guide I linked earlier), you can either trust the incoming DSCP, or apply a DSCP and map to an appropriate forwarding queue. You might have to check how your device is marking packets with DiffServ and whether any device between it and the MS is altering it in any way (by default, for example, Catalyst switches remark DSCP back to 0)
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