Relationship advice

Hi I have 2 kids.. a 5 yo and a 4 month old. My husband took a position at a plant 4 hours away and we see him every other weekend. It's been hard.. like really hard..

Some trends I've noticed is that he won't text me unless I message him first.. unless it's to ask if I did something for him.. our son has a phone (my mother's line on our account that we kept after she died..) and he hasn't messaged our son at all. Like not even once on whatsapp. He doesn't ask how our kids are, he doesn't ask how I am. We have had 2 video calls where I had to push conversation or we just wouldn't be talking.

The only defense for this I can think of is that he has pretty severe ADHD and he once showed me a video tmif a guy who also has ADHD and that if we aren't in front of him his ADHD all but forgets us (the guy phrased it as human object permanence)..

If this is an ADHD thing I'd like to try and come up with ways for him to be reminded to message my son or I (maybe an alarm at 2:30 when my son gets home from school)... if this medically isn't how it works, I feel I need to talk to him about family engagement when he is away.

It's not like he's working insane hours.. usually 8-6 with a lunch.. he's back at his hotel, watches TV and goes to bed when he feels like.

That's one issue... then when we have him here he's just not as engaged as I hope he would be with such limited time.. few weekends ago I told him I needed him to take the kids for a while after being their primary caregiver non stop for 2 weeks... like I'm burned out and just needed some time to take a nap and take a long hot decent shower.. the day before I let him sleep in til noon then we had lunch but he was on the phone the entire time then I took th kids to my son's friends house and didn't make him go thinking he needed a break... I truely don't ask for much.. he doesn't do any household chores except his own laundry to pack for his work trips..

Am I asking too much from someone with ADHD? This all seems new even though we have been together for 11 years.. but we never had an instance of him working long distance like this...