No flawless playback, stuttering, stuck on an ad, auto pauses... the first two are problem for all but the auto pausing is when using proxy/vpn, something you can't avoid at work, we tried many vpn companies neither solved our problem. Spotify must make the web player friendly to vpn or we not going premium anymore.
Same problem here. Stuttering / pauses every time an ad reloads.
For a temporary fix you can delete the ad container with the developer tools interface.
( ctrl-shift-i to open developer tools, select the "Elements" tab, click the "Select an element in the page ... " button, and hover just above the advert until you're over the element div.ads-container , select that, and then in the developer window it should have highlighted <div class="ads-container"> , right click that and select delete )