Play from Vu+Solo 4k to Vu+ Solo2

[colheath]

Hi, I have for some time been successfully viewing live content and recordings on my Solo 2 from the Solo 4k, using client mode and with network mount for the recordings. Today however live content is fine but I cannot access the recordings. I've tried deleting and adding again, rebooting boxes, router, it's driving me mad. I can't work out how it's been working well form months and now doesn't.

Any help appreciated,
ta!