Gateway ethernet fails to connect when powering on while network is not yet available

[ptr727]

I have been having problems with the gateway not coming online and then z2m fails to start while it is waiting for the coordinator to respond to network requests.
The problem typically happens after a power failure, and to restore connectivity I need to power cycle the gateway.

Today I replaced the batteries in the UPS powering my network closet, that also powers the gateway.
As soon as I powered the UPS on the gateway powered up, but it took a couple minutes for switches to come online.
Z2M was not working, the gateway was not responding, I could see the network activity light on the gateway was not doing anything.

As soon as I power cycled the gateway the gateway and Z2M worked again.

Expectation: Network connectivity should be resilient and periodically reconnect without requiring power cycle.

May be related to:

• coordinator not responding to zigbee2mqtt? #133
• Ethernet component cannot reconnect when manual_ip is configured esphome/issues#2783