We are sorry to hear about that you downgraded from ESET Internet Security to ESET NOD32 Antivirus since you have lost protection from brute-force attacks that Network attack protection included in EIS provided and could prevent attackers from stealing or encrypting files.
With EAV it's also more difficult to troubleshoot network communication issues. Please install Wireshark, start logging and then manually run update. When update fails, stop logging, compress the log and upload it here along logs collected with ESET Log Collector.