There is no bundled Internet at Home and Mobile contract. Those contracts are in every case separated contracts!
In case your mobile contract with the Smartphone has been rejected, your Internet at home contract will not be influenced at all. But it might be, that the Internet at home contract will also be rejected in case that the Schufa score is bad. And please note that there are more indicators and not only the score on the website. Especially if there have been multiple "bad" indicators like new credit cards, new bank accounts, multiple different contracts, maybe even not paid, might indicate that you won't be able to pay for all of them and thus contracts get rejected.
This usually happens if you opt for a contract with a high monthly payment and a high value phone - sometimes it's then better to buy the phone for the retail price, e.g. pay the phone directly and not over time, and then only get a sim-only tariff plan without smartphone payment.
And please also note that if there is no Schufa score for you (because you're too new to Germany -or- because there have been no "positive" indicators in the past), then the Schufa will calculate a score based on the where you live. This might lead to negative entries in case people in the area around are not trustworthy, even if this doesn't match your personal situation.
