Based on old posts from Anthony:

You are basically turning off the feature that allows the remote end to
stop sending audio but have FS still process the stream.
The timer will allow the channel to read at the specified interval even
when the other side stops sending audio.

If the other end has a clock sync issue with FS or FS does not have a
reliable timing source, it could cause your problem.

When timer-name set to none, it does blocking
reads on the audio vs timed ones.  If the other end has a skew in clock
freq with the FS then it will timeout erroneously.  Having blocking reads
ensures you only read audio when there is actually some there.  Basically
this timer-name set to none makes FS behave just like asterisk does by
default.