I don't see MS-DOS or Windows 3.11 as much as a problem as having 30 year old hardware. Bad capacitors on the motherboard and oxidated (rusty) contacts for memory and ISA cards can break the system, while the software itself can be ran in a virtual machine on newer hardware, if needed.
I ran MS-DOS in an airport for several years and it was just fine. Windows 2000 was available, but not needed for the task at hand, while a reboot was way faster with MS-DOS than any Windows at that time and a reset was the solution for 99% of the incidents, the rest was hardware-related.
In terms of replacements, a Raspberry Pi would be more than enough in terms of computing power, with some decent (non-microSD) local storage. Cheap, simple and I guess the cost of writing the MS-DOS app from scratch should cost about the same as that admin for 1 year.
Retro gaming enthusiasts have been creating mini-PCs first starting with industrial computers (386) built for CNC machines, and have recently been getting custom PCBs made like the Pixel x86: https://youtu.be/B8WfiRRvQXo?si=lbDZymYKATkT66pf
I guess these systems are certified, so changing the hardware with a platform that is basically an emulation (based on the first video) requires re-certification. At that point, changing the entire system to something more modern seems like the better option.
I ran MS-DOS in an airport for several years and it was just fine. Windows 2000 was available, but not needed for the task at hand, while a reboot was way faster with MS-DOS than any Windows at that time and a reset was the solution for 99% of the incidents, the rest was hardware-related.
In terms of replacements, a Raspberry Pi would be more than enough in terms of computing power, with some decent (non-microSD) local storage. Cheap, simple and I guess the cost of writing the MS-DOS app from scratch should cost about the same as that admin for 1 year.