Seems like it may be overheating.

There are two thermostats that need to be checked for continuity, the thermal cut off and the hi-limit". If found to be bad, they need to be replaced. Here is the kit you need.Here is a video to show you how to check them.

if its a solid piece you can take a set of sheet metal snips and cut some 3/4 to 1 inch slices down the tube end and continue around the pipe at about 1 inch intervals, this will allow you to ease the pipe over the venting from the dryer and also over the vent cap leading to the outside, then use metal tape ( not screws, they tend to grab lint on its way out ) to cover the splices, I always use a 4" hose clamp on mine to ensure they stay on and in place

The thermal cut-off , which is the small t-stat looking piece located at the top of the element housing ( on vertical mount elements ) or the far front of the element housing ( on horizontal mount elements ) , is usually the cause for no heat .

duel 30 amp for an electric dryer

Good Luck

100mm or 160mm or 4" or 6"

The vent may be stopped up, or the vent hose crimped so the air cannot escape, you can check the air flow at the vent on the outside of the house while the dryer is running.
try cleaning the vent and the lint screen with a vacuum cleaner, you may need to replace the vent hose, this should solve the problem

Most common cause of this is a clogged venting going to the outside to test this remove the vent from the back of the dryer and run a load if it drys ok them you know you have a venting issue and will need to be cleaned out if not plz repost and we can look deeper into it

Yes, the semi-rigid metal flex tubing is recommended because it resists crushing, crimping, collapsing and heat. The old plastic flex hoses would collapse easily, develop more clogs, melt and rodents could chew through them easily. When installing a new flex hose, the SHORTER and STRAIGHTER you can keep the run, the better. The more bends you have, the greater possiblity you have of creating areas where lint can clog. I hope this helps you. Post back if you need further guidance.

You have a severly blocked vent, its not removing the moisture to the outide but instead getting trapped in vent.reccomned reventing unit with solid duct pipe, not the vynyl flex tubing and mke sure the outside exhaust port is totally free of obstruction a well

The vent is a 4 inch round opening.  Per the manufacturers specifications, you should only use 4 inch solid metal vent pipe, not plastic or metal foil vent pipes.