If you mean 802.1Q, then by looking into the RTCS source code there is some logic implemented around 8021Q priority tags. By default this option is off. Set the RTCSCFG_LINKOPT_8021Q_PRIO to 1 in user_config.h:
#define RTCSCFG_LINKOPT_8021Q_PRIO 1
to have RTCS send and receive Ethernet 802.1Q priority tags.
If you mean 802.1Q, then by looking into the RTCS source code there is some logic implemented around 8021Q priority tags. By default this option is off. Set the RTCSCFG_LINKOPT_8021Q_PRIO to 1 in user_config.h:
#define RTCSCFG_LINKOPT_8021Q_PRIO 1
to have RTCS send and receive Ethernet 802.1Q priority tags.