Also, y'all could try installing from the tarball but the Perl version you have is probably too old for some stuff. We now target 5.10, as the oldest distribution still being maintained is CentOS 6 and that's the Perl version it has.
If it's the same error, it's the same problem. Also, SLES 9 reached end of life four years ago! What are you guys doing? You're playing with fire running unmaintained operating systems. Super dangerous, especially if connected to the internet.
Ah, OK, understood. Be careful with that server, then! That's scary, I hope it's not connected to the Internet, especially not directly, but even with a firewall I'd be nervous about it. Would it be possible to run the old OS in a VM, so you only use the old OS for that one specific task? (Then again, I guess if the machine is dedicated to the task of only managing radios, it's fine as long as you're super careful.)
I don't know who Icom is, but you should file a ticket with them, if their software doesn't run on a maintained version of CentOS/RHEL.. They're the ones doing you wrong, here. ;-) I don't think it's reasonable to assume new versions of software should run on very old versions of operating systems...if you're OK with old software, then old versions of Webmin should also be fine. You can disable notifications about updates in Webmin->Webmin Configuration->Index Page Options->Show Webmin updates on...
CentOS 5 reached end of life nearly two years ago; there's no more maintenance happening from the CentOS folks, so it is no longer safe to run CentOS 5. The RPM version in CentOS 5 doesn't support newer format RPMs. Jamie continued to use the old format for a while, but at some point we have to move forward. I'd strongly recommend you migrate to a new system running a maintained Linux distribution. CentOS 7 will be supported until, I think, 2023, so it would be a great choice.
There's no way any interactive app has ever worked in the popup shell in Authentic Theme. It's impossible; it is not an interactive terminal and never has been. The popup is simply a nicer way to use the "Command Shell" module (which is also not an interactive terminal). It will eventually be an interactive terminal, but it is not currently one, and has never been one in the past. There is an interactive terminal module available for Webmin called AJAXTerm, which you can use for most interactive...
We saw this on the software.virtualmin.com servers, and just updating the CA fixed it for wget. Some clients won't complain, because I guess they already recognize the Let's Encrypt cert, but wget was failing. Maybe try making sure you have the latest Let's Encrypt CA? (If you update it on download.webmin.com, it should sync automatically to the mirror server within an hour.)
I have no idea what seedbox from scratch is, but it sounds like it's a DIY type of distribution...so, you wanted DIY, and you got it! You're going to have to figure out where all the paths are in your system and tell Webmin about them, so it can find OpenVPN and it's related tools. Since I've never seen the distro in question, and have no idea what it is derived from, I can't even guess about where they might be. Sometimes, you can copy an existing config from a distribution that is similar...like,...