A21 is a four-antenna AC2100 wireless signal extender designed for large-sized home users. The 5G wireless rate can reach up to 1734Mbps, and the 2.4G wireless rate can reach 300Mbps. It is equipped with four external omnidirectional antennas and 4x4 MU- MIMO, compared to AC1750 and AC1900 products that use 3x3 MU-MIMO technology, is faster and can better meet the signal coverage of the whole house of large-area home users, and enjoy high-definition online video, live broadcast and large-scale 3D games. A21 also has an external Gigabit Ethernet port, which can provide a more reliable and faster network connection for wired devices such as set-top boxes, smart TVs, PS4 and PCs, and is more flexible in use.