Hi @blueste
Welcome to the Sonos Community!
I’m sorry to hear about this issue you are having with playing content to a group of speakers and the track restarting when you do so. This should not be happening.
I have not heard of this occurrence before - if rebooting your router (by switching it off for at least 30 seconds) followed by a speaker reboot does not resolve this issue, I recommend you get in touch with our technical support team who have tools at their disposal that will allow them to give you advice specific to your Sonos system and what it reports.
I hope this helps.
"Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein