Dear frustrated mother-in-law,
Yes, your son does have a problem and those children do need his attention. Since you are the mother-in-law, you can’t say anything to him, but your daughter (or his mother or father) can.
I would encourage your daughter to do a couple of things.
First, praise her husband for his strengths as a father. I’m sure she can find some strengths in him.
Then, tell him it would be so good for the kids to have “just Dad” time and see if he would be interested in taking one or two or all of their kids camping. He could go away on the weekend or pitch a tent in the back yard. If he doesn’t want to camp, ask him what he liked (or always wanted to do) as a boy and then encourage him to do that with the kids.
I have found that if you can get men outdoors, they use phones and electronics less (and it’s best if he would go somewhere that the internet is unavailable!). If he won’t go alone, tell her that he should plan a trip for the family which involves hiking, camping, canoeing or anything like that. Then, he can go and see how much he enjoys the kids’ company without the phone.
Don’t nag him because this will only backfire.
She must approach him by telling him how meaningful he is to the kids.
She can encourage him to read them stories at night (because the kids love to hear him read), say bedtime prayers (they like to hear him talk), and at dinner time, she should make a family rule that no electronics should be used at the table to encourage healthy dialogue between all the kids and you. She can even have him tell the kids the rule so that he can’t violate it.
You get my point. Men respond much better to praise than criticism.