Any cell routers with external antennas?

I have a KVD21 with firmware 1.00.18. In the first week I got it, the performance is extremely inconsistent. I sometimes got single digit up and down, but also triple digit down and single digit up in a good day. It was  very random but generally very bad during the day, better later in the night. It was unacceptable. Then I bought a Waveform 4x4 panel antenna. Since then, the performance has stablized. I generally get at least 100 down and 20 up during the day and 180 down and 30 up during the evening. The ping numbers are also greatly improved, always sub 20 ms without load and 300ish ms under load.  I am not even putting the antenna outdoors.  I put it right on the desk, next to KVD21, facing the direction of the tower through a glass window.  The tower is about 1 miles away without line of sight.

I also tested the antenna outside. I could get 400 mbps. But the trouble to install the antenna outside is way too much for me. 

The performance has been rock solid for two weeks.