default or selected kernelversion does not have config value CONFIG_APOLLO_ELPLUS.
Result is shown for kernelversion 5.5.18

Apollo 3c505 support


Linux Kernel Configuration
└─> Device Drivers
└─> Network device support
└─> Ethernet (10 or 100Mbit)
└─> Apollo 3c505 support

Say Y or M here if your Apollo has a 3Com 3c505 ISA Ethernet card.
If you don't have one made for Apollos, you can use one from a PC,
except that your Apollo won't be able to boot from it (because the
code in the ROM will be for a PC).