Why does it say "Checking your connection…"?

On slow Wi-Fi the app waits with you — "Checking your connection…" and "Loading your account…" count up while a slow link answers; the error card appears only when something has genuinely failed.

Because your connection is slow, not broken. On poor Wi-Fi — a hotel, a cellar bar, a busy café — the app's quick security check and the first read of your account can take a while, so instead of guessing that something has failed it waits with you and tells you what it is doing: "Checking your connection…" with a counter of how long it has been (for example "Checking your connection… 25s"), then "Loading your account…" (or "Loading the portal…" on the staff portal) once the check has passed. After about 20 seconds it adds that the connection looks slow and that it will keep trying; it keeps waiting for up to a minute while the link is still answering. Reload the page sits underneath the whole time if you would rather start again.

On the sign-in page the Sign in button does the same — a "Checking your connection…" line under it while the check runs, then "Still signing you in — your connection looks slow" if the sign-in itself takes more than a few seconds. Only when the sign-in service genuinely cannot be reached do you get "We couldn't reach the sign-in service on this connection. Check your Wi-Fi and try again." with the button ready to try again.

You only see the "We couldn't load your account" card when something has actually failed — the link went dead, or your details never arrived even though the link was answering. The card says which, and Retry picks the check up again with the same counter rather than a blind countdown. The longer story, including the security check itself, is in Why does it say "having trouble verifying your connection"?.