Well, it appears to have been IPv6 causing those syslog errors, after all.
I ran the following commands, as best as I could determine from that thread, and that seems to have stopped the syslog errors.
uci set 'network.lan.ipv6=0'
uci set 'network.wan.ipv6=0'
uci set 'dhcp.lan.dhcpv6=disabled'
uci -q delete dhcp.lan.dhcpv6
uci -q delete dhcp.lan.ra
uci commit
uci commit dhcp
/etc/init.d/odhcpd restart
uci set network.lan.delegate="0"
uci commit network
/etc/init.d/network restart
/etc/init.d/odhcpd disable
/etc/init.d/odhcpd stop
uci -q delete network.globals.ula_prefix
uci commit network
/etc/init.d/network restart
Thanks again guys.