Ugh, I spoke too soon. This did indeed work when I tried /etc/init.d/network restart, but it did not survive a full device power cycle.
I noticed the following in the output for logread:
Fri Mar 29 16:10:12 2024 daemon.err odhcp6c[2681]: Failed to send RS (Address not available)
Fri Mar 29 16:10:13 2024 daemon.err odhcp6c[2681]: Failed to send SOLICIT message to ff02::1:2 (Address not available)
Configuration of 'lan' is the same from the message above.