I have just checked my NTP server, and it's funny that I also see a bad time.cloudflare.com, among a set of 4 random NTP servers from the FreeBSD pool.
Even if the time.cloudflare.com is much closer to me than the other servers, at 8 ms delay, it also has a large offset of around 3 ms from the true time.
While that is much worse than the other servers, it is still 2 orders of magnitude away from the hundreds of ms of your case.
Besides the 4 random servers from a pool, I also use 4 individually selected NTP servers. For example, because I live in Europe, one of them is the NTP server of the French astronomical observatory (Observatoire de Paris, SYRTE).
I have been using NTP for decades and I typically see on my own NTP server (from my home) an offset less than 0.2 ms with a jitter between 1 ms and 2 ms, while the delays to the reference servers vary between 8 ms and 250 ms, with most between 40 ms and 60 ms.
I have configured NTP on a large number of computers and I have never seen offsets above 10 ms, but it is true that most of them had reasonably good Internet access, over Ethernet, TV cable, optical fiber or high quality wireless links.
I can imagine that a very bad Internet access, with highly variable delays to the reference servers might confuse NTP, but I have no longer seen such cases since around 2001/2002, i.e. since the last time when I have used dial-up access over a phone modem.
Even if the time.cloudflare.com is much closer to me than the other servers, at 8 ms delay, it also has a large offset of around 3 ms from the true time.
While that is much worse than the other servers, it is still 2 orders of magnitude away from the hundreds of ms of your case.
Besides the 4 random servers from a pool, I also use 4 individually selected NTP servers. For example, because I live in Europe, one of them is the NTP server of the French astronomical observatory (Observatoire de Paris, SYRTE).
I have been using NTP for decades and I typically see on my own NTP server (from my home) an offset less than 0.2 ms with a jitter between 1 ms and 2 ms, while the delays to the reference servers vary between 8 ms and 250 ms, with most between 40 ms and 60 ms.
I have configured NTP on a large number of computers and I have never seen offsets above 10 ms, but it is true that most of them had reasonably good Internet access, over Ethernet, TV cable, optical fiber or high quality wireless links.
I can imagine that a very bad Internet access, with highly variable delays to the reference servers might confuse NTP, but I have no longer seen such cases since around 2001/2002, i.e. since the last time when I have used dial-up access over a phone modem.