DTR is generated on HW or SW connection. Whenever you connect the device or open/connect the terminal etc. Persistent connection is without the change on DTR.
serial -> ethernet -> serial converter for remote programming
This is not clear where the Arduino(s) are in the pipeline. Is one Arduino being used to program another Arduino? Is the goal something similar to esp-link but using Ethernet instead of WiFi?avrdude has a network option -Pnet:<ip addr>:<port num> so the remote side does not require a serial port.avrdude -Pnet:<ESP addr>:2323 -> network -> ESP8266(esp-link) -> Arduino board
I thought that perhaps I could use a second microcontroller or circuit to monitor the incoming AVRdude data and trigger the target Arduino to do a reset. Will this work, or does the reset have to occur some time before the program data reaches the target Arduino?