I have a repeatable issue that was present in Firefox but is now fixed (automatically, nothing I did). Hoping that we can find a solution in Thunderbird also. I have a Mac (Intel) with a VPN connection (wireguard) to my office just for office traffic. Regular traffic bypasses the VPN. Every time the machine goes to sleep for an extended amount of time (overnight), Thunderbird's DNS resolutions fail. I have 8 different IMAP accounts (including 2 gmail accounts). None are using the VPN connection but direct email address. After sleep, there is no more connections and the culprit is DNS failures on all accounts. This is the only software (and I have many running simultaneously!) that is affected. Solution is to shutdown Thunderbird and restart. Resetting the dnscache on mac doesn't work. *SOMETIMES* disconnecting from VPN and reconnecting resets it, but not always. I had the issue with both Mozilla products (Firefox and Thunderbird) and was just living with it. But a recent update in Firefox fixed it on that software. I haven't looked at the release logs to see if anything changed. So I'm guessing there is something we can do with Thunderbird to reset the DNS or something else when it comes back from sleep. Let me know if any more information would be helpful. Current Version is Thunderbird Nebula 128.7.0esr (64-bit)