NVG589 issues with WiFi and rebooting

I have had this model modem for 4 months or so and it's already been replaced 3 times (each time with different issues) this time the issue is wifi.

I use wifi for a number of items but I notice often that my iPad and iPhone won't connect to it. When this happens it either shows no wifi name or it shows the name and then asks  for the password but when I put it in (yes I am putting it in correctly 100%) it will just ask for it again and again. Then 10 minutes later it will connect without asking me the password. This is in from 1 room away (10 feet).

Also I noticed tonight that the modem rebooted it's self, don't know if this happened before but I was just looking at it to see if the wifi was green as I could not connect to it.

Now, I suppose it's possible that it's been rebooting when I have the wifi issues (I am normally in the next room when it happens) so I don't know if it's related.

I did search for NVG589 rebooting and found lots and lots of people complaining about the same thing. Some had the modem replaced multiple times but never solved the issue (or did not come back to post the solution).

Anyway I am looking for any advice. I wish I could just buy an aftermarket good modem. My older one (2 part modem with power bank) was very reliable for years but it finally died.

NVG589 W/battery, internet and voip both uVerse.