Which number to use
Use the login number attached to the MT5 account inside MetaTrader 5. It is the account identifier that MT5 uses together with the exact server name.
A broker client ID, prop firm dashboard ID, email login, or support ticket number can identify you in a portal but may not identify the MT5 account that exports trading history.
Why a wrong ID can look like a credential issue
If the login number belongs to a portal instead of MT5, the server can reject the connection even when the investor password you copied is correct for a different context.
The useful check is therefore login number, exact server name, and investor password together. Changing only one field can keep the same failure if another field still points to the wrong account.
Safe support evidence
Support should ask for the exact server and a non-secret account identifier, then rely on product-side connection evidence. Passwords should stay inside the app connection flow.
Screenshots can be useful only if they do not expose secrets and if they show the MT5 account/server context clearly enough to resolve the mismatch.
Key takeaways
- Use the MT5 login number, not a broker portal client ID.
- Check login number and exact server name as one pair.
- Keep passwords out of screenshots and support messages.