Make sure the TP link is accessing the external antenna. ( I dont know if the spark have firmware limitations ) I dont know if 5G uses MIMO like 4G but @coffeebaron should ... losses occur for this ...

But it does what TP-Link claims ... connect to a 4G mobile service, which it makes available for others via an 802.11ac WiFi connection. You may like Rio Cybersecurity Wi-Fi Router review Zyxel ...