DRAC on PowerEdge 2950

We are trying to configure DRACs on all of our Windows servers (mostly
2012 R2).  All R710s and R910s we have tried just worked with little
effort.  But, we haven't been able to get any PowerEdge 2950s to work.
In all cases we're using a shared NIC; the DRAC has a different IP
address in the same subnet.

I can ping the DRAC IP address on three 2950s; on two I cannot.
A web browser cannot get a response from the 2950s.
If I run "racadm getsysinfo" on a pingable 2950, I get
ERROR: RACADM is unable to process the requested subcommand because there is no
local RAC configuration to communicate with.  (Same command on an R710
spits out a lot of info.)  There definitely is a DRAC; I can configure
it by hitting ctrl-E during boot or with OMSA.

I suspect a DRAC firmware update may help.  I got a bootable ISO of
drivers for 2950s from
https://www.dell.com/support/article/us/en/19/sln296511/updating-dell-poweredge-servers-via-bootable-media-iso?lang=en
It ran for ~half an hour on one 2950 and updated some things, but I
think not the DRAC firmware.

Systems-Management_Firmware_D8GP9_WN32_1.65_A00.EXE from
https://www.dell.com/support/home/us/en/19/Drivers/DriversDetails?driverId=D8GP9&fileId=3009896398&osCode=WNET&productCode=poweredge-1950&categoryId=SM
says "not compatible with your system configuration".

I have firmimg.d5 from f_drac5v165_A00.exe but I don't know how to
install it without either a working DRAC or working racadm.

I can ssh into the servers where the DRAC is working, but not into the
ones where it is not working.

I know TLS may be a problem for web access.  We've disabled TLS 1.0
and 1.1 by group policy, but a web browser from a machine not in the
domain also couldn't connect.

In DRAC BIOS setup, the top box says 1.28 which I assume is the
firmware version.  BMC was 2.1 before update, now 2.5.

Any suggestions on how to update the DRAC firmware or any other
actions we should take?  Thanks.