Note that since IP (and thus UDP, thus HTTPU, thus SSDP) is by definition a
best-effort delivery protocol, sometimes you won't hear back from one Roku or another. It's a fact of life.
In the code i wrote that will result in that Roku IP not showing in the list of results (i wait 1000ms to collect all responses). The drop rate is not particularly high - e.g. on my home WiFi is <10% with 3 Rokus:
n_fails = 0
for i in range(1, 100):
rokus = get_ecp_urls()
n_fails += 3 - len(rokus)
print i, 'runs,', 100 * n_fails // (3*i), '% failure rate'
$ python oo.py
1 runs, 0 % failure rate
2 runs, 0 % failure rate
3 runs, 0 % failure rate
4 runs, 0 % failure rate
5 runs, 13 % failure rate
6 runs, 22 % failure rate
7 runs, 19 % failure rate
8 runs, 16 % failure rate
9 runs, 14 % failure rate
10 runs, 13 % failure rate
11 runs, 12 % failure rate
12 runs, 11 % failure rate
13 runs, 10 % failure rate
14 runs, 9 % failure rate
15 runs, 8 % failure rate
16 runs, 8 % failure rate
17 runs, 9 % failure rate
18 runs, 9 % failure rate
...
However, since the code you used waits forever for a response, in some cases (e.g. no Roku or lost reply) it will never return, just "hanging" there. Plus, since it waits for the 1st response only and ignores the rest - we end up with a
race fondition and you may never hear from some slower Roku on WiFi since a faster, wired one will preempt it. Yes, network programming is hairy...
