MSA 2050 Jumbo Frame 'issue'

Hello All

We have an MSA 2050 connected through it's own VLAN, via a HPE FF5700 to 5 HPE Gen10 ESX 6.7 servers.

We have created the datastores in VM on the SAN.

I have read the best practice guide for the MSA which states the Jumbo frame size should be set to a maximum of 8900.

If we set this, on all relevant interfaces and devices, we can see the datastores but have no write access to them from ESX.

If we set the jumbo frame to 9000 we have full access with read and write to the datastores.

Can someone please explain why? Am i missing something? It works with 9000 but not 8900

Thanks