I would like to add my 3 cents (good grief, It turned into a $30 'Mobby Dick' novel). It's been said before - the support from both Duet and the community is incredible. There have been many occasions where I was impressed about the amount of patience and knowledge that is shown every day.
Having said that, there are only so many things that can be done when one is sitting in front of a computer, totally removed from the actual device that is causing issues. Things that might be immediately obvious sitting in front of the Duet may take days and days to sort out remotely.
I have had my fair share of "operator problems", Some I have had sorted by people here, some I have fixed myself after bouncing the issue off people here and they got me thinking the right direction and then there were too many issues that just took hours or even days of screwing around before the light went on.
I have learned an incredible amount by pounding my head against the wall and sticking with a problem and reasoning things out. You probably don't want to hear that but immersion into the whole 3D printer scene is pretty mandatory if you are going the "self built" Duet route. It is not a product that is turnkey - it is a small part of a large and complex machine. A machine that Duet has no control over.
It is not fair to purchase a car engine and expect the manufacturer to be able to figure out why the car that you built around the engine tops out at 50 km/hr for some reason.
In addition to all that, the Duet 3 and RRF3 is a new product that is still being developed as I type this and changes to the software happen on a regular basis. It is not a 'stable' product as the Duet 2 series is. There is a steep learning curve to go from RRF2 to RRF3. I still work with a Duet2 but have migrated to RRF3 which was a big step for me. A step that isn't for everybody at this stage.
I can only suggest to stick with it and eventually it will 'click'. This applies to the Duet to some extent but I would say that it is less a Duet issue and more of an issue of the whole 3D scene.
I don't recall what your particular issues are. Maybe you are doing something that has never been done before, maybe you are doing something that is a real challenge even for a person that has been involved in 3D printers for many years. You can't expect things to just magically work. Thankfully, the community around the Duet shows incredible patience and sometime I must admit, more patience than I would ever be able to muster.
Sometimes it helps to approach a problem from a different perspective. Start a new thread along the new direction and maybe we can help you that way and eventually get to your current problem via a back pathway.
I find that sometimes it is necessary to take a break for a couple of days. More often than not, this will clear up my thinking and new avenues will open up.
Last but not least, you can't expect to purchase all the bits and pieces for a printer and expect to have a working unit in a given time frame. It requires time to develop a new product and when you build a new printer that is exactly what you are doing.
Sometimes, when you NEED a printer in a month, it might be best to buy a commercial product with full support and satisfy your desire to build a printer when you don't have the pressures of needing it in a month or 6 .....