We use "afrihost" - with no password and no spaces or additional charaters (and don't include the " ").
You may need to remove any other APN you have, such as myMTN, in order to connect.
Please also ensure that you have set Afrihost as your APN for 3G and LTE (depending on your device) as well as for your personal hotspot. Otherwise your SIM may switch over to a default APN (which is billed by another service provider).
We highly recommend using our APN notifications to ensure that you are always connected to the right account.
A device reboot usually helps new APN settings stick :)