Changing the DNS could help. I've seen it work for similar issues in the past. You can update the DNS on your Xbox using the steps below:
1. Open the Xbox Settings
2. Go to All Settings
3. Choose Network
4. Go to Advanced Settings
5. Choose DNS Settings and select Manual
6. Enter 8.8.8.8 as the Primary DNS and 8.8.4.4 as the Secondary DNS. This is the public Google DNS, but if there's a different DNS you'd rather try us...
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