RT-AC56U achieves a wired bidirectional throughput of up to 1250 Mbps. For wireless throughput the 2.4GHz band provides an average up/down throughput of 110Mbps and the 5GHz band provides an average up/down throughput of 525Mbps.
Many reports indicate stability issues with the 2.4 GHz band. While ASUS acknowledged the issues, the firmware fix they issued that was supposed to fix these issue has had limited success.