We recently had a situation with a customer where they would randomly receive the famous H202 or H505 error in Quickbooks 2014, 2015, 2016 which would prevent users from connecting in multi-user mode.

After going through all the regular troubleshooting steps as described here:
you will still randomly get the error.

Turns out the issue was related to the fact that the server had an additional IP address, which was required for the environment. There was also a DNS entry as Windows will automatically register the extra IP/DNS entry. So doing a DNS query for the address would return two IPs

This causes Quickbooks issues. So the simple fix was to add a host entry in C:\Windows\System32\Drivers\etc\hosts for the server to point to our main IP. It’s been rock solid after applying that fix.

If you are having issues with your network and need us to take a look, feel free to contact us for a free quote.