Streamer app not recognising streamers on wired network using GS116v2 but does when using GS108v4

Happy New Year
I have a question about communication between multiple streamers (Linn DSM’s) , Netgear switches , a Talktalk router and an IPhone

iPhone 13 ios18
Talktalk Sagecom 5364 router with FTTC
Netgear GS116v2 and GS108v4switches
Linn DSMs various with latest software

The Linns would autoplay when switched on but became flakey allowing the linn app(white) finding the rooms. I solved this originally by plugging them directly into the Router

With the prospect FTTP and using the Talktalk eero set up, I thought would try connecting everything through the GS116 switch but it became intermittent and I couldn’t group different Linns together

So testing began
Plugged the Linns into the router and all good
Then plugged them into a brand new switch (GS108v4) attached to the router (only Linn nil else) and all good
Then I tested each port on the GS116 switch by attaching a PC and using a broadband speed checker app on each one and they all worked
Then I plugged the Linn boxes and only the Linn boxes to the GS116 switch and they only worked intermittently
Then I plugged the linn boxes into the new GS108 switch on their own and all the other kit (TV’s,PC’s, network printer , access point in the garden) into the bigger GS116 switch and everything works. The switches each were connected to the router by their own cable

Does anyone have any ideas?
Obviously I have a solution but would prefer not to have to use 2 switches, because there are only 2 internet ports on the eero, one for the modem and one for the switch, when the full fibre comes.
Is the bigger GS116 switch broken? Or is it some other issue?
I have tried to log into the switch but cant
Thank you for your time and expertise