From waveform.com:

If you're looking to get the absolute best data rates for your LTE or 5G hotspot, using cross-polarized MIMO external antennas is often the best option.

Our MIMO Panel External Antenna Kit for 4G LTE/5G Hotspots & Routers includes everything you need to mount your external antennas, as well as the adapters necessary to connect the MIMO antenna to your hotspot or LTE router.

Our MIMO Panel antenna offers up to 9 dBi gain between 1710 and 2700 MHz, and 6 dBi gain between 600 MHz and 900 MHz.

https://www.intel.com/content/www/us/en/support/articles/000005714/wireless/legacy-intel-wireless-products.html#:~:text=MIMO%20increases%20receiver%20signal%2Dcapturing,surplus%20antennas%20to%20good%20use.

Worked great for T-Mobile home 5G service, moved - no longer needed since new HOA fee covers fiber internet. 

https://www.tomshardware.com/service-providers/t-mobile-home-internet-revisiting-5g-connectivity-for-the-home-after-two-years

see AMAZON  /Antenna-Waveform-600-2700-Boosters-Adapters/dp/B09QB1YWPY?th=1