I had the same issue with my previous router, which was a newer tri-band router...

If you have an apple tv, then you could try streaming music to that - in that way you could then identify if it is the phone or ipad that is the problem with the drop out. I would still advocate forgetting wireless and hardwire it in - even as a test to rule out any other interference.

I found that the best way of streaming music for me, was to use an older Apple TV hardwired > DAC > Beosystem and use the remote app on your iphone or ipad - that way the Apple TV is streaming all the music through a network cable and the iphone is only used to control it.

Sorry just read that it is hardwired!

I would still try and stream to an ATV and see if that drops out, then at least you will know if it is the playmaker

Did you set the Playmaker to a fixed(!) IP adress?

Not yet. Don't understand the format of primary and secondary DNS info. On my mac, the format is

10.0....

2a02:fe0:.....

I guess the first is the primary DNS and the second is the secondary?

Should i enter them the way they are?

Secondary DNS shouldn't be required as the Airport is a single device anyway.

Just enter the same IP you have on your Mac, something like "10.0.0.1". That other set of numbers is IPv6, never mind that without getting into details.