If you are not certain what specific mobile settings you should use with your particular SIM card, it is always a good idea to contact your SIM provider and ask this question.
According to the information, available on the internet ( source_1 or source_2 ), "CHAP" authentication is not used by Tele2 Sweden (only PAP with two specific APNs). Most of support APNs does not use any authentication at all, therefore in router's "Network -> Mobile" menu you should select "Authentication method: None".
Have you tried using same SIM card in any other device? Was it connecting to same Tele2 Sweden network? With what mobile settings?