Migrate same Configuration from Big IP 4000 Device into BIG IP2000 Device

same firmware is best, so upgrade the 2000s unit to 12. as you will overwrite the configuration later on it shouldn't be that difficult. you might want to do factory reset first so there is no configuration that can bother the upgrade.

see for factory reset: https://support.f5.com/csp/article/K13127

a restore of the 4000s UCS archive is the first thing to try afterwards, with the no-platform and no-license flags.

for those flags see: https://support.f5.com/csp/article/K14906