apt key management failure any full online solution or key download method

Using a Debian9 server, behind a proxy, I need to install a docker client. So to get a key I use the commands: apt-key adv --keyserver http://WHATEVERKEYSERVERITRY --keyserver-options http-proxy="http://proxy.myclientdomain:4128 " --recv-keys 7EA0A9C3F273FCD8 Executing: tmpapt-key-gpghome.BO0J96KdNM/gpg.1.sh --keyserver http://WHATEVERKEYSERVERITRY --keyserver-options http-proxy=http://proxy.myclientdomain:4128 --recv-keys 7EA0A9C3F273FCD8 gpg: keyserver receive failed: no key server available I tryied all keyring/MIT/debian etc... keyservers I know (about 5/6) The proxy is not the cause, apt-update , ping to www.google.com & so on ... are just OK. I think there is another root cause somewhere else... but it is not possible, **really not**, neither to change anything neither get infrastructure information. So the question is: is there another method to get the key 7EA0A9C3F273FCD8 100% online, generating a file I can then copy/paste?