I had similar problems with Salt. With Swisscom it works perfectly for me. Have you ever logged into the router on your PC? You have to enter the IP at the bottom of the device into the browser. This will take you to the router settings. You will also find the password at the bottom of the router. Then go to the "network settings" and at the bottom "profile". If you have the Sunrise card in there, it should say Sunrise. If it is empty, you have to create a new profile and configure it manually. Normally this should always happen automatically, as it does with you and Swisscom. If it doesn't happen automatically, then manually. The APN settings are that, or whatever it's called. Google "Sunrise APN" and you should find something. You have to enter it there and then it should actually work.

Symptoms when using SALT Mobile network (all or the other Brad band providers using SALT broadband network like Lidl Abo or GoMo) :
- Router has to be restarted daily,
- some pages works some not,
- sometimes page has to be reloaded or is stuck

After long troubleshooting with Wireshark: Issue is SALT Double IP address NAT and Encryption which impact TCP\IP MTU size.

Solution:
- Log into the router and go to "Network Setting" TAB find " MTU SIZE " default value is 1500 (bits) - change it to 1400

Explanation
- at the time of writing this post the true accepted value was 1470 bits, but if you do not know how to test it it is better to set it to 1400 and forget about the problem forever

Cheers!