SAP B1 MTD Connection Fix

My SAP Business One system stopped sending VAT returns to HMRC right after the last update. Each attempt ends with the MTD add-on throwing a “temporary error” during submission, so nothing reaches the HMRC gateway... (Budget: £250 - £750 GBP, Jobs: Accounting, API Integration, Documentation, Intuit QuickBooks, SAP, Technical Support, Testing / QA, Troubleshooting)