High Iron Ore - where to find?
 

Where can I farm High Iron Ore?
I have not found it in Deshan - as was suggested on youtube.

That's very old information. The resources you find are a combination of the crafting skill and combat level. E.g. max level, no blacksmithing will still frequently find iron, but also sometimes rubedite. https://elderscrollsonline.wiki.fextralife.com/Ore

Means: If your crafting level for smithing is too high you won't find it "on purpose" anymore, just random.
Either build a toon with lower crafting skills to farm it, or buy it in stores then.

Looking at it the other way round, if you need high iron ore for your current character to level up blacksmithing, you are most likely to find it.

If you're trying to level up crafting on an alt, you'd need said alt do the gathering as well... or at least pass on the survey reports to him in order to clean out the mother lodes.