Thanks, I found the problem by inspection of src/lib9/_p9dialparse.c.
IPv6 is indeed the default when using an address of tcp!*!17034
/* translate host */
if(strcmp(host, "*") == 0){
ss->ss_family = AF_INET6;
((struct sockaddr_in6*)ss)->sin6_addr = in6addr_any;
}else if((he = gethostbyname(host)) != nil && he->h_addr_list[0] != nil){
So, setting the address string to tcp!dell-openbsd!17034 fixed the problem.
My Linux machines actually have an IPv6 address, the OpenBSD box does not, so that explains the difference.
Ole-Hj.