You didn't provide any release details, but I suspect you installed something old &
unsupported.
The last
alternate ISO Lubuntu released was in 2018-April (details can be found here -
https://help.ubuntu.com/community/LX.../Alternate_ISO) but that release completed its three years of supported life in 2021-April.
The
alternate ISO was less flexible, but it worked on hardware with 768MB or less of RAM which was below that required for the
primary ISOs. Your usage of the
alternate ISO seems strange given you've >1GB RAM.
The EOL detail for Lubuntu 18.04 LTS can be read here - -
https://lubuntu.me/bionic-eol/
Ubuntu 18.04 LTS release announcements tell you
where Lubuntu being a flavor, had 3 years only, ie. 2018-April through 2021-April.
Also if you go to Lubuntu's web site (
https://lubuntu.me/downloads/) I don't see any ALTERNATE ISO offered (
there hasn't been for year+), so I'd check where you downloaded it from, as google will offer
fan & fake sites as well as the legitimate site for Lubuntu downloads (
depending on your language used in search). It's up to the user of google to detect which are which (
though I've noted some security extensions warn when going to a illegitimate Lubuntu site).
Did you use an official Ubuntu site? or a Lubuntu site? (
I suspect not!).
If you want to a
fan site, they usually don't do the download themselves (
saving bandwidth costs), but point your download from a Canonical/Ubuntu site; so I'd check that's where it was from. If you used a
fake site, I'd check where it was from, and what you actually installed. I'm mentioning this due to what I suspect is an EOL release being used given the
alternate ISO hasn't been supported by Lubuntu more than a year.
