Hey everyone, I'm in a bit of a jam here. I've been working as a .NET developer but recently got thrust into the role of the sole admin for our Windows servers after my boss decided to make a change. Now, I've got to manage migrating our entire business to a new server because our old servers are being phased out at the end of the month. To make matters worse, after the migration, I've noticed that only about half of our clients can reach our API, which is obviously causing a lot of frustration. I thoroughly tested everything before the switch, so I'm stumped. I've confirmed that the firewall isn't blocking anything, but clients keep receiving a SERVER-RST response. The only notable difference is that our old server had three different IPs for various subdomains, while the new server is using a single shared IP. Could this be the issue, and what can I do to troubleshoot this problem further?
5 Answers
I see a lot of chatter about DNS, but OP mentioned SERVER-RST responses from the new server. If it were purely a DNS issue, wouldn't the old server still be catching those API calls instead? Just trying to figure it out too!
Wow, that's quite a situation! Have you thought about asking one of the affected clients for a screen share? Sometimes the issue could be as simple as their local DNS cache not updating. It might give you some insight into what they are seeing on their end.
One key point to consider is that your clients need time to adjust to the new server and IPs. A strategy that might help is implementing some load balancing. Also, try lowering your DNS TTL even further before the migration to keep it from taking too long for everyone to find the new setup.
Thanks for the tips! Definitely looking into load balancing as a longer-term solution.
Another thing to check is whether any clients have specific cipher or TLS issues. It’s also useful to check if the same clients keep getting reset and whether it changes among them. Identifying patterns might help you find the root of the issue.
I’ll definitely look into possible ciphers or TLS settings. Thanks!
Sounds like you might need to ensure that your clients' networks allow-list the new IPs. We've run into this many times when moving to new servers. Ideally, clients should confirm they can connect to the new environment beforehand. Also, lowering your DNS TTL to about 60 seconds a few days before the cutover could help speed up the transition.
Great point! It could be something deeper related to the server configuration or client settings.