I've been involved in radio and telecomunications for over 50 years and a lot of that with Ham Radio. The secret to high speed data and internet is the best signal you can get which involves not only testing different positions around the home but different antenna's as well. For internet speed testing head over to OOKLA on speedtest.net for a reliable speed test.
Basically, the stronger your signal is, the faster your connection will be. It also goes without saying, the worse the signal is the slower the connection and sometimes even dropping below 1MBs. A lot of 4G routers have the facility to connect external aerials to increase the aerial gain and therefore the connection and download speeds. The position of the router plays a crucial part as well. Try your router in all windows of the house, especially upstairs to find your best signal.
The next option is to look at an external aerial. Using an aerial outside will definitely give you a big signal jump and there are basically two types of external 4G router antenna, an omnidirectional which is easy to set up, all you have to do is get it as high as you can with the supplied cable and a directional aerial such as a Yagi which looks a bit like a smaller version of a TV aerial. There are Pro's and Con's here, the omnidirectional Aerial doesnt need to be pointed in any direction, just get it as high as you can with the supplied cable and the downside is less gain than a Yagi aerial but simple to set up. The Yagi aerial can have extremely high gains, much higher than other aerials but has to be pointed at the nearest 4G mast to achieve this.
I live just under 1 mile from my nearest mast and whilst playing I have achieved speeds close to 400MBs on occasions. I use an omnidirectional aerial which gives me speeds around 200MBs, I chose this aerial simply because I can use this with my router in my motorhome with very little setting up.
