Thanks @cocoon, and I owe a correction: when I said in https://xcp-ng.org/forum/post/104865 that 6.4 would make these alerts disappear for good, I overstated it. If I'm reading the code right this time, the XO server sends a ping every 30 seconds stamped with its own clock (https://github.com/vatesfr/xen-orchestra/blob/master/@xen-orchestra/rest-api/src/events/event.class.mts), and the browser compares that stamp with its own clock and shows the banner once the gap passes 40 seconds (https://github.com/vatesfr/xen-orchestra/blob/master/@xen-orchestra/web-core/lib/packages/remote-resource/sse.store.ts). So https://github.com/vatesfr/xen-orchestra/pull/9681 widened the margin from 32 to 40 seconds, but a browser whose clock runs ahead of the XO server by more than about 10 seconds would still see it. That might be why @GregBinSD saw it on the Windows PC and not on the tablet, though that's only a guess on my part. I'll pass this on to the XO team, since comparing two different clocks looks fragile to me, but they'll know far better than I do whether there's a reason it's done that way.