Hi,
I am getting very bad range with my Spark.
I'm using an OTG cable to connect my phone to the controller.
I have tried using both 2.4 and 5.8ghz channels and I am using a signal booster but I am only getting around 300m (1000 feet) before the video signal cuts out.

I am flying in a suburban area.

What am I doing wrong???

I'm using a Samsung Galaxy A6+ phone.

Please help.
Thanks.

Flying your Spark in a built up area is not a good idea - including suburbs. You will get all sorts of interference from home/business WiFi networks also operating on these frequencies. I couldn't even do my first IMU and Compass calibration in my garden because of interference from the aforementioned and the amount of iron/steel in my surroundings building's structures. Luckily i have a vast expanse of open countryside less than mile away. Here the only interference I get is from walkers/runners passing by that are wearing bluetooth fitness trackers. I am still able to fly more than a mile from my homepoint in this location.

Interference I guess try flying where there is less building.

This is actually pretty good range.
Note the following spec:

    Max Transmission Distance
    2.412 - 2.462 GHz (unobstructed, free of interference)
    FCC: 1.2 mi (2 km); CE: 0.3 mi (500 m)
    SRRC: 0.3 mi (500 m); MIC: 0.3 mi (500 m)
    5.745 - 5.825 GHz (unobstructed, free of interference)
    FCC: 1.2 mi (2 km); CE: 0.18 mi (300 m)
    SRRC: 0.7 mi (1.2 km); MIC: -

Please note that figures are for ideal conditions.
One way many users extend their Spark range is switching to FCC mode.

Hello and good day thesotman. I am sorry to know that you are having issues with the mobile device that you are using on your DJI Spark.  Have you tried using a different mobile device for us to check if the issue still persist? Upon checking  the mobile device that you are using ( Samsung Galaxy A6+ ) phone. I am sorry to say that the mobile device that you are using is still not recommended for your DJI Spark. Actually, there is a  possibility that the Samsung Galaxy A6+ phone will work, however, since it's not yet optimized with the DJI Go 4 application we cannot guaranteed the stability of the DJI Go 4 application if this will work all the time while using the specific device.  We highly suggest you use the compatible device that was listed on the recommended mobile device list below to avoid any problem. Thank you.