20/3/2018 5pm update:
HMRC has informed us that their live server is once again available and service restored. You are now able to make Payroll submissions to HMRC.
We have received email communication from HMRC that they are experiencing difficulties with their live server. HMRC's Service Availability page are in the process of being update.
In the mean time, our customers will not be able to make Payroll or VAT submissions through QuickBooks Desktop.
In QuickBooks Desktop, you'll see an error message 'QuickBooks encountered a problem with your network'. We recommend that you check back at a later time to resubmit.