I’ve checked it here on my end and found out that there’s an on-going issue with QuickBooks Online when accessed through the updated iOS. I’ll refer you to another post in the Community, which will provide updates as they become available:

Current status (9/23/2016): Our engineers have determined […]

Resolution for 'another post issue: 'Quickbooks Online is not working on Safari 10.0.' available: Yes.

The another post issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the another post issue yourself by looking for a resolution described in the article. If it is a complex another post issue or you are unable to solve the issue, you may contact us by clicking here or by using other another post support options.

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