This one better?
andy@RT-AX86U_Pro-4368:/tmp/home/root# tcpdump -v -n '(icmp6 and ip6[40] == 134) or (udp and port 547)' -i vlan101
tcpdump: listening on vlan101, link-type EN10MB (Ethernet), snapshot length 262144 bytes
21:54:46.232600 IP6 (flowlabel 0x0eb8a, hlim 1, next-header UDP (17)...