Nice. Suse Linux was my first. But that came. Couple of years later. CD-ROM was already a thing by then.
Regarding the modems. My internal PCI 36.6 modem actually got me shorter latencies than using a 50k modem over serial bus. I have no idea why. But my 50k modem was at the very last years of modems. Many where getting ISDN and cable by then.
Perhaps, like me, your serial port was driven by an older UART chip like an 8250 [0] which could be a bottleneck for modems faster than 9,600 baud.
I remember in teen years phoning the local computer shop every week asking if they had the 16550 UART [1] serial cards in stock yet to upgrade my 486DX4-100 to get full 28.8kbps from my modem. Can't remember if they ever did.
I think the 16550 was faster largely because it had a larger buffer, so it wouldn't wait or drop data as often when the CPU was slow/busy.
Regarding the modems. My internal PCI 36.6 modem actually got me shorter latencies than using a 50k modem over serial bus. I have no idea why. But my 50k modem was at the very last years of modems. Many where getting ISDN and cable by then.