Hi! I need some help.. I'm Swedish, so please forgive my english!

My Deco M4 mesh system in our house is intermittently dropping it's connection. Or more specific, there are several units within the system that's looses it's connection. As an example, the LG tv loose connection once almost every night we watch tv, but my iPhone still got internet connection at the same time as the tv drops its internet. So it feels almost like it's the mesh system that doesn't do well with these units. After the drop, the units usually gets reconnected about 5-15 seconds later. 
 

These units are well within the range of the nearest Deco unit, so it shouldn't be a range issue. It's our LG tv, a surveillance camera, an Apple TV 4K and sometimes our iPhones that's usually have these problems. 

Things I've tried: 

- Deselecting "mesh" for these units

- Setting them up for "high priority"

- restarting everything, resetting everything 

- Tried different settings with ivp6 and such

But nothing helps. It's so annoying.. 

I have theee M4 v4 units and one v2 unit in the mesh system, but I'm pretty sure the problem was there before we added the v2 unit.

Can anyone help, please?