Rain uses 1800 MHz and 2600 MHz frequencies so you will need an antenna capable of that. I am using LPDA-0092-LTE and getting a gain of 14 dBi even though max is suppose to be 11 dBi. A-XPOL-006-10M with a gain of 11 dBi and A-XPOL-0002-V2 with a gain of 9 dBi should also both work. All have SMA connectors so you will need an SMA to TS9 adapter x 2 . Not sure if there is a recommended antenna.
These antenna will improve your signal reception and therefore your download and upload speeds, they will do nothing for your wifi coverage or range