Hi,
I want to confirm this issue, and report, that it is not truly fixed with firmware 1.16.
We have 7 pieces DP832 here in an automated testsystem, and some are very vulnerable by mDNS packets, others are not. Our PC runs Linux Mint, which has installed avahi-daemon by default (which sends these mDNS packets). We have no Apple products here. One supply failed nearly every 10 minutes of operation. Others had no proplem for days. They run all the very same firmware (same binary, updated via USB flash drive, MD5 Sum: 3ebdd0f64636b67976a5c075945dc88f DP800Update.GEL)
The misbehaveour isn't the same all the time. Somtimes the device is still controllable via buttons, sometimes it freezes completely, sometimes it is pingable, sometimes not. The common problem is, that it isn't reachable any more via TCP connetions on port 5555. Our script times out after 0.3 seconds. The only workaround is a power on reset. We tried reconnecting the ethernet cable or hitting "back" twice to enter local mode with out any luck.
The Solution:
I uninstalled the avahi-daemon on the Linux Mint test system:
sudo apt uninstall avahi-daemon
Further we kept the network clean from any devices with mDNS.
Before that I saw many mDNS packets in wireshark, and the devices failed regularly. Now they ran 1 day without any single problem. Wireshark didn't capture a single mDNS packet.
Thanks to @edgelog for that hint with the mDNS packets!
Greets, Karl
Very vulnerable device serial number: DP8C213603321 with officially installed RS232 and Ethernet upgrades.