Yes, the threads on this thing sucks, worst of all the mods I have. The Bluetooth is useless as you have to keep re-enabling it every time it goes to sleep. The overall build quality is horrendous, I have a bubble that was formed on the plastic surrounding the screen right in the view of the OLED as well as spots on the inside of the plastic window (possible bubbles or adhesive or resin spatter as well as multiple spots right on the OLED from possible adhesive or resin spatter (the screen was obviously not cleaned prior to final assembly), the B with the Bluetooth underneath was silk screened by a buffoon, it is 3-4mm to the side (not centered).
While in the menu mine has on more than one occasion fired and would not stop until I remove the battery or let the 10 sec safety kick in. The information that is displayed on the OLED is useless as you have to enter the menu to change it to see either Battery, Ohms, Temperature or Output, yup only one can be displayed at a time and the info is only shown as you press the fire button, goes dark as soon as you let go, SMOK expects you to use your phone to see ALL the info at once but to do that you have to constantly re-enable Bluetooth and have the App reconnect to the BEC, total rubbish and a waste of time.
I have emailed SMOK with all these issues and they will not respond... Last SMOK product I buy, I will stick with Joyetech. I have an EVIC Supreme as well and honestly it puts this BEC to shame, the Bluetooth is just gimmicky and adds no real benefits that I can see. The EVIC Supreme can be had for the same price if you find it on sale.
Sorry for the ranting but it should connect and stay connected until the mod goes to sleep, It does not have to be paired to the phone as the App handles the connection. There is nothing you can do on the BEC itself other than turn the Bluetooth Off or On. I would suspect it is an issue with the BEC seeing as their quality control department if one exists are a bunch of blind buffoons. I would try connecting it to another phone and if that doesn't work I hope your vendor will exchange it because SMOK obviously doesn't care to respond to their customers. I purchased mine direct from a Chinese distributor, this thing is not even worth the $59 dealer cost.