WiFi
Is it stable? Bandwidth?
WiFi is infrastructure, and like all infrastructure you only notice it when it fails.
Stable connectivity is something you either planned for or scrambled for mid-session. If any part of your workshop depends on the internet (a shared board, a video, a live tool, a backup presentation stored in the cloud), you need to know the network situation before participants arrive.
Ask the venue directly: is there a dedicated WiFi for facilitators, a guest network, a bandwidth cap? If you are expecting 20 people all on the same connection, find out whether that is realistic. Have a fallback for anything critical: download the slides, cache the board, bring a mobile hotspot.