one site i am unable to ping by domain name, but can by its IP address

been at this for a couple hours and it is driving me nuts. using cmd, i can ping google, and it pings just fine... any site for thta matter, but there is one program that when i try to ping it, it comes up with nothing, if i try pinging it again by its ip address, i get packets back... i have tried other computers (win10, and win 7) and i am able to ping using the domain name just fine! i have checked my HOST file for any entries, and there are none. i have rebooted router, rebooted the pc with the issue, ipconfig /flushdns, rebooted again... nothing! what gives? i am unable to login to this software with this issue.. i am unable to use the IP to log in either, it quickly reverts to the domain name, and then of course fails... i do not know what else to check? i have checked my firewall... but see no obvious issues there. again, i can ping any domain name by name and get packets back on this... it is just one certain domain, and only on this pc. within my router i have access profiles, all MY pcs are in the same profile, i am able to ping the domain name just fine via the ROUTER as well. just this one windows10pc (pc is up to date with updates)
any ideas?
thanks!
p

What is the domain and IP?

i am using the synology router, and it was a setting under the package THREAT PREVENTION.. weird that it was singling out this one pc only though.. i disabled it for this pc and, tada, worked just fine. i will look into why it singled this pc out and not the others (that were also preotected by the threat prevention package.
thanks!
p