PS4 app suddenly unable to see NAS or PMS on PC

Hi,

In the last few weeks, the PS4 app has been unable to see the PMS either on my NAS or my PC (automatically or manually). The issue will last for a couple of days then resolve itself. All other players are unaffected, and all other network services on the PS4 are fine - including the PS4 inbuilt DNLA Media Player which can see and use the NAS and PC devices when the PS4 app can’t
I’ve made no changes to the PMS nor the network that it is on.

Any one have any ideas?

Thanks

Bumping this