A stable 2 Mbps will watch a show. An unstable 20 will stutter.
That is the whole answer, and the word doing the work is stable.
Why steadiness beats speed
Live video arrives continuously and is played as it arrives. There is only a small buffer, because a live auction cannot run thirty seconds behind — you would be bidding on an item that had already closed.
So a connection that drops for two seconds produces a visible stall, however fast it is the rest of the time. A slower connection that never wavers plays smoothly.
What this means in practice
Mobile data works, and it is often steadier than contested wifi. It uses data like any video, so if you are rationing, join for the item you want rather than the whole hour.
Wifi at a distance from the router is the usual culprit, not the plan you pay for. One room closer often fixes what an upgrade would not.
Other people streaming in the house is the other one. The problem is contention, not capacity.
If a show is stuttering
Switch network. Wifi to mobile data, or back. This is the fastest test and often the fix.
Move closer to the router, or take the case off a hot phone — heat throttles the radio before it throttles anything else.
Reload. A stream that lost its place does not always recover alone.
Check whether it is the browser rather than the line, because the two look identical. Which browsers work?
You can still bid on a bad connection
Worth knowing, because people give up when the video stutters. Bidding is tiny — it is a few bytes going to a server, nothing like the video coming back.
So if the picture is rough but you know what you want, you can still bid and still win. Your screen may be a moment behind, so tap the amount the app offers rather than typing one you read a second ago. What if two people bid at the exact same moment?
And if you drop out entirely, your bid stands. Leaving the room does not withdraw it. If I leave the show, do I lose my bid?
For sellers going live
Broadcasting is the harder direction — it needs upload rather than download, and home connections are usually much weaker going out than coming in.
Test it in a rehearsal rather than discovering it in front of a room, stay in one place while live, and keep the phone plugged in. Can I practise before going live for real?
More: what you need to watch a show, which browsers work, what happens if my connection drops mid-show.