It will most probably pop out a windows to put username and password. If you never change its password, you may need to open it using its default password. For TMnet streamyx, below is the default password for different router. Refer from:
http://www.simonandjun.com/wordpress/2007/10/29/tmnet-modem-default-password/
1. ZTE modem
* IP Address: 192.168.1.1
* Username: ADSL
Password: expert03
* Username: ZXDSL
Password: ZXDSL
* Username: admin
Password: telekomst
2. KASDA modem:
* IP Address: 192.168.1.1
* Username: admin
Password: telekomst
3. ArtNet modem:
* IP Address: 192.168.1.1
* Username: admin
Password: telekomst
* Username: admin
Password: admin
* Username: admin
Password: password
4. Triz modem:
* IP Address: 192.168.1.1
* Username: admin
Password: aaaaaaaa
5. Aztech modem:
* IP Address: 10.0.0.2 OR 192.168.1.1
* Username: admin
Password: blank
* Username: admin
Password: password
* Username: admin
Password: admin
6. Billion modem:
* IP Address: 192.168.1.254
* Username: admin
Password: password
7. Huawei modem:
* IP Address: 192.168.1.1
* Username: admin
Password: admin
8. Hyundai HSE-220 Modem:
* IP Address: 192.168.1.1
* Username: ADSL
Password: ADSL
* Username: admin
Password: ADSL
* Username: root
Password: root
9. Riger DB102:
* IP Address: 192.168.1.1
* Username: tmadmin
Password: tmadmin
10. TP-LINK MODEM / ADSL2 / ROUTER:
* IP Address: 192.168.1.1
* Username: admin
Password: admin