OK been seeing alot of talk on this subject, so i started testing it in diffrent environments. here are my findings,

everytime that i had problems switching to 2.4 ghz there was alot of wifi signals around, tryed to switch just would not, yes i could force it by shutting down and so on but signal would be bad,lag droping and so on, anyway have alot wifi signals by my house cameras routers ect. tryed to switch from 5.8 to 2.4, no way would not kept going back to 5.8. otg cable or none.

SO i shut down every thing wifi around, cked on phone and no signals from any wifi.  loged in went to dji go spark controller hooked to dji, went to switch to 2.4 warning came up about switching wifi picked a channel and bam switched over np just like that no otg cable, flew the spark everything perfect no lag no dropping could go as far as i wanted, 5.8 would drop at 550'      2.4 went to 1000' and could gone further just didnt want to fly over ppl.

looks like when there is to much interference on 2.4 the spark will not switch and thats a good thing. mabey dji can do something to fix this mabey not but if you fly in the middle of no where it not a problem to get the max distance,

will be going up to the highest point here and try this to see how far i can go anyway hope this helps ya , and try it out yourself

ultimately it will keep reseting back to 5.8ghz every time its restarted..    my advise, use OTG, and plug in turn off wifi on tablet/phone, get spark and RC and app synced together like normal then hold power button on the spark after everything is synced up, hold it until you hear a single beep, let go, then on controller press and hold Pause + FN + C1 to preform RC relinking, hold it till it beeps rapidly at you for a couple seconds then let go, let the two figure out what's best channel/channels in the area together, the RC should shut up moment the spark and RC found best fit.

the  tablet/phone should show clear image again right away and be lag free or mostly lag free no more than 1/8th or 1/4th sec delay. if it isn't clear or has significantly lag like half second or more,  try relinking process again but this time try to hold the spark up higher in the air to pick up any stray signals so it will mark them to avoid,  it should relink and be better.  

doing this while on OTG with phone/tablet not using wifi or bluetooth allows for the spark and RC to search better...doing it on OTG will cause the app to disconnect from the aircraft but not the RC.

1000 feet is typical before video interruptions start occurring in congested areas, but you still have control over the spark with minor video losses.    complete video loss for multiple seconds = complete spark control loss, the signals are bound together but controlling it needs less bandwidth than syncing video so ti can usually stray on little longer until full interruption occurs.

few additional tips:  

line your body and RC up to match where your spark is you can use the radar compass thing to line it up so both facing same way.

increase your altitude with range.   if my area was perfectly flat and only trees and buildings up no more than 80 feet, at 1000 feet i would fly my spark around 250 feet in the air it increases your RF line of sight range.. this also helps prevent the spark from getting too much interference from houses and buildings below it.

ImHereToCrash Posted at 2017-8-7 12:35
ultimately it will keep reseting back to 5.8ghz every time its restarted..    my advise, use OTG, and plug in turn off wifi on tablet/phone, get spark and RC and app synced together like normal then hold power button on the spark after everything is synced up, hold it until you hear a single beep, let go, then on controller press and hold Pause + FN + C1 to preform RC relinking, hold it till it beeps rapidly at you for a couple seconds then let go, let the two figure out what's best channel/channels in the area together, the RC should shut up moment the spark and RC found best fit.

the  tablet/phone should show clear image again right away and be lag free or mostly lag free no more than 1/8th or 1/4th sec delay. if it isn't clear or has significantly lag like half second or more,  try relinking process again but this time try to hold the spark up higher in the air to pick up any stray signals so it will mark them to avoid,  it should relink and be better.  

dji says otg not tested and recommends not to use it, i had a bad experience with it, controller shut down in flight, spark was only just taken off grabbed it

TMUSVI Posted at 2017-8-7 17:11
dji says otg not tested and recommends not to use it, i had a bad experience with it, controller shut down in flight, spark was only just taken off grabbed it

i never had controller shut off like that.. you may have a bad cable or adapter.  or maybe hooked up host side to the wrong end.  host side is RC.  

i have only tested using these, had ideal results.

https://www.amazon.com/gp/product/B00N9S9Z0G

https://www.amazon.com/Joyshare- ... apter/dp/B0156X6ZB8   ( dont reccomend, good in a pinch and as backup incase you forgot all other cables,  but loose and not best possible connection)

https://www.amazon.com/dp/B00ZL7U5ZW