Pro 4 camera disconnects and now cannot be added to account

[arlo_user_ca]

Connected Pro 4 camera approx three weeks ago to network (direct wifi not hub) and worked fine until yesterday. Trial subscription was oeprating although I have smart suscription with otehr devices.

Last night Pro4 went off line (only pro 4 other cameras fine) .Showed discocted from network. attempted t o resynch to the same wifi network with no success. After many atemots gave up; removed Pro 4 from account and tried to reconnect as new device. Camera QC code succesfully indentified but would not connect to wifi standalone. Gave up. Tried synching with the (4000) hub. Hub goes in synching mode but does not find the camera despite being right next to it. Hub has two other devices connected to it. IOS phone shows looking for camera to no avail.  

Why is nothing straightforward with Arlo ? My leagcy cameras work great and now Arlo want to obselete tehm hence my acquistion of an Arlo Pro 4 to 

[arlo_user_ca]

addend.

Moved Pro 4 right next to router wifi signal- which is 100 feet away from the Hub and tried to connect with main wifi. 

Yellow LED flashed for a while (first time seen this) then blue synch occurred. Much to my surprise synch was succesful BUT not with the wifi directley  as expected. It had synched with my Hub (original intention) some 100 feet away !! I really have no idea how the synch process actually works,why devices with strong signals ddisconnect  but it is contary to all the intructions regarding adjacencey ect.  Is it just random luck ? The Pro 4 is now back on my account