Could be a connection problem of the plugs or you have connected more than 25 channels to one control unit. Try plugging the low-light channels near the control unit. If the problem "moves" to another light, you have too little current.

I also had problems connecting recently. Tried them all, hard and soft reset. Without success. I contacted Nanoleaf support and got a new control panel. Try the soft reset by pressing the on and off button together for 10 seconds. If that still helps, try the hard reset, disconnect the power, hold down the on and off button and plug in the power during the process, release after about 10 seconds.