connection time too long or connection failed with some smartphones

[mdido]

Hello, I'm having too long connection times or failed connections with some android smartphones (for example samsung A7). Is there a way to decrease connection times?

I'm using nRF52832 with SDK 15 and softdevice 6.0

[Kenneth]

A sniffer log of a few situations would be useful to make sure I understand the problem. Is the problem that the peer (phone) is not sending connection requests, that the connection requests are not received, or that the connection is established but the initial connection interval is very slow? Or all of the above?

I assume you have seen the following:
https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/what-to-keep-in-mind-when-developing-your-ble-andr 

[mdido]

Thank you for the link.

In most cases the connection is established but the initial connection interval is very slow. Sometimes the connection fail.