ARP - problem in some network

Hello, I have problem with connectivyty in one network.
I use many devices with W5500, but in one company network can not connect- ARP ping is not possible from any PC.
If I put my new device with W5500, the switch don’t make APR table a I cant ping this device.
But if I put to my device MAC adress from any anothoer device (from PC explample) it’s wotk 100% good. ARP ping work in second.
Switch block (filter) MAC? NO! if I put new PC to switch it’s work and ping to PC no problem.

Any idea? where problem is?

Hello, semiart

Basically, W5500 has no MAC address.

You need to put available MAC address in W5500 for network.

Thank you,