I had been using this Quad with TBS unify pro v3 for months and always use R3 / R5

Since few days ago i thought the VTX is broken bcoz i can not get any image

Checked the wiring and cable.. Seems nothing wrong

Then I autosearch via goggles got A Band and receive pictures

Checked the VTX channel via LUA Script Frsky QX7
Looks. Like vtx had been reset to
A 1 25 mw

I tried to set R 3 800 mw via QX save then
Retrying message appear and failed

Tried to set A 3 800 mw then save
It works and i can fly with it

my questions is

Is that mean my VTX broken ?

Will it matter for A band.. R BAND.. E band..?
What is the different for image connection range and clarity

Yeah, that don't sound right.

That said, it probably doesn't matter unless you're in a noisy RF environment (near cell towers, around buildings with lots of wifi, that kind of thing) or flying with other people and you need to avoid each other's frequencies. I fly solo and haven't moved off F7 ever.

In theory the band and channel should have no bearing on the power output. In reality, the power output can vary pretty wildly from one frequency to another, but you'll never know without some expensive testing equipment.

try changing it in Betaflight OSD? LUA script can be funny at times..

Tried as Oscar said.. Works perfectly

Definitely LUA script sometime error

Thanks guys