Haha, I feel sorry for you. However, the restaurant industry in our country is lacking in standards and is basically unquantifiable. You can eat the same burger at any KFC and it will taste almost the same, but you can't get the same flavor of Kung Pao Chicken at the same restaurant.

From your pictures, it looks like you have a good quality oven, at least much better than the guy's who gave you the advice. We are currently on the market for home ovens belong to the soon-to-be-obsolete products, the oven's materials are relatively thin, the sealing performance are not very good, so the quality of good and bad. Some ovens boast that they can heat up to 220 degrees, in fact, due to technical problems, the temperature simply can not reach. More reliable is embedded oven, the price is a little higher, basically more than 3000 yuan.

Practice with this oven first. You've gained valuable experience. I believe that next time, you will be successful.