Experiencing a strange delay in name resolution for Home Assistant

Why does using http://homeassistant.local:8123/ takes time to resolve, which pops a message “Connection Lost” and “Reconnecting”, where as using the http://IP_Address:8123/ never drops.
I tried to add a local DNS record to the device in my router but that failed with the message that homeassistant.local is reserved for use with mDNS.

Fairly good explanation here: