idracadm gives ERROR: Unable to connect to RAC at specified

We recently acquired a set of new servers, Poweredge R430 with idrac 8 cards, and Poweredge R440 and R540 with idrac 9 cards.
Our old servers which those replaced had been R710, R415 and 1950 with idrac 6 cards.
We run Redhat Enterprise Linux 7.5 on the new servers.

We have always used the utility program racadm to remotely turn servers on or off, depending on the requirement of more or less capacity in our small web server farm.

Now I found that the utility provided by DELL for RHEL 7 no longer worked. It worked with the old machines with idrac 6 cards, but not with the new machines.
What happened is this:
idracadm -r xxxx  -u xxxx  -p xxxx getsysinfo
ERROR: Unable to connect to RAC at specified IP address.

The same command used against a idrac 6 card worked.

What version of idracadm did I use?
I had downloaded the latest package offered by Dell
OM-MgmtStat-Dell-Web-LX-9.1.2-2965_A00.tar.gz

and unpacked it.
From the rpm archives in the unpacked set I installed
srvadmin-idracadm-9.1.2-2965.12849.el7.x86_64.rpm
srvadmin-argtable2-9.1.2-2965.12849.el7.x86_64.rpm
srvadmin-omilcore-9.1.2-2965.12849.el7.x86_64.rpm 
srvadmin-hapi-9.1.2-2965.12849.el7.x86_64.rpm

This gives the utility /opt/dell/srvadmin/bin/idracadm which I used and which did not work.

Dell support was sadly not very helpful, working apparently only from documentation with no access to actual machines.
I updated the target machines to latest BIOS and idrac firmware (on basically new machines) without any success.

I tried the Windows version of racadm, which comes in a version 9.1.3. It worked.
But that was no help for me, as we have normally no Windows machine in our environment.

Finally, I found the solution myself.

I looked once more at the set of rpm files in the unpacked archive. There is one called
srvadmin-idracadm7-9.1.2-2965.12849.el7.x86_64.rpm
I could onyl guess that idracadm7 means that it is for idrac 7 cards.

There are also these rpms
srvadmin-racadm5-9.1.2-2965.12849.el7.x86_64.rpm
srvadmin-racadm4-9.1.2-2965.12849.el7.x86_64.rpm

and there is no explanation what these are for.
Anyway, I installed this set of rpms:
srvadmin-idracadm7-9.1.2-2965.12849.el7.x86_64.rpm
srvadmin-argtable2-9.1.2-2965.12849.el7.x86_64.rpm $
srvadmin-omilcore-9.1.2-2965.12849.el7.x86_64.rpm 
srvadmin-hapi-9.1.2-2965.12849.el7.x86_64.rpm
which gives me
/opt/dell/srvadmin/bin/idracadm7

That one works, with idrac 6, idrac 8 and idrac 9 cards.