Just unpacked new phantom 4pro+, updated firmware and app, went out to fly, good connection but signal of "Radio Channel Quality - poor" flashing, followed by "Strong interference. Fly with caution."
Top of screen showed "Overall Status - Latest Firmware" but when clicked on said "Aircraft locked. update to the latest version" Checked both app and firmware correct on latest versions.
Plane would not fly.
Also mentioned conflict with mobile phone (iPhone 6S) so removed and later changed frequency from 2 to 5

Just a beginner so probably something simple.. How to stop the conflict and get craft flying.

Radio channel quality is about where you are flying as much as anything. We share the radio frequency with a squillion other transmitting devices, the worst of which are private WiFi routers. You may be right in the middle of a nest of routers, try getting out into the countryside and see how you go.

You have to be careful were you set the machine down, stay away from cars and remember there might be underground power. Best bet is to use a heavy rubber pad right on the ground. Avoid setting the machine on concrete since there's usually steel rebar, also plastic tables have steel supports.  Don't set the transmitter too close to the drone either.

Fly safe Mike

Mike Mas Posted at 2017-7-8 19:51
You have to be careful were you set the machine down, stay away from cars and remember there might be underground power. Best bet is to use a heavy rubber pad right on the ground. Avoid setting the machine on concrete since there's usually steel rebar, also plastic tables have steel supports.  Don't set the transmitter too close to the drone either.

Fly safe Mike

All of those things are compass issues, they have nothing to do with the radio communications channel, which is the problem the OP reported.

Use DJI Assistant 2 to update everything. I had to do it 2-3 times with the latest firmware / NFZ data for some reason.

I think this is a bug with the latest firmware regarding radio interference. I used to fly 4+ kilometres but with the latest firmware it is about half that now with constant 'Strong interference' warnings, even out in the middle of the desert. My Mavic has no issues at all. Hope they fix it in the next firmware!

It's a problem with the latest firmware switch off the wifi or put in into airplane mode you want get the problem then DJI have told me they are looking at a fix

remembertosmile Posted at 2017-7-9 01:36
It's a problem with the latest firmware switch off the wifi or put in into airplane mode you want get the problem then DJI have told me they are looking at a fix

I will try switching off the WiFi or putting it in airplane mode to see if that works. I have been having the same issue for the upgrade and even worse after the latest firmware.

Bug... Plus 4.1 app has not been updated yet. The iOs 4.1.3 has. I have both and the Plus still does it. Just set it for 5.8mhz and Custom for now to avoid it but it you leave it on 2.4mhz and auto the message is more annoying than anything as I'm told. I never had performance issues. Hopefully, there will be an update for the plus soon.