I just checked with the netdrive plugin from bare OS/2. At first it did not work. But then I changed my settings to use the "Remote directory: /pub" and it works. I'm pretty sure it worked years ago without this setting.
I also use a password starting with - although I'm not sure if this is necessary. See welcome text of hobbes ftp server -
19:26:04.300: hobbes.nmsu.edu: 220-If your FTP client crashes or hangs shortly after login, please try
19:26:04.300: hobbes.nmsu.edu: 220-using a dash (-) as the first character of your password. This
19:26:04.300: hobbes.nmsu.edu: 220-will turn off the informational messages that may be confusing your
19:26:04.300: hobbes.nmsu.edu: 220-FTP client.
19:26:04.300: hobbes.nmsu.edu: 220-
19:26:04.300: hobbes.nmsu.edu: 220-New uploads should be placed in /pub/incoming.
19:26:04.300: hobbes.nmsu.edu: 220-
19:26:04.300: hobbes.nmsu.edu: 220-OS/2, Java, and various forms of multimedia archives are accepted.
19:26:04.300: hobbes.nmsu.edu: 220-
19:26:04.300: hobbes.nmsu.edu: 220-NMSU is an educational institution which permits free access to its
19:26:04.300: hobbes.nmsu.edu: 220-ftp archives. No money is charged for access to the archives or the
19:26:04.300: hobbes.nmsu.edu: 220-distribution of its contents. NMSU has no affiliation with Walnut
19:26:04.300: hobbes.nmsu.edu: 220-Creek, makers of the Hobbes OS/2 CD-ROM.
19:26:04.300: hobbes.nmsu.edu: 220-
19:26:04.3019:26:04.300: hobbes.nmsu.edu: 220-Login: anonymous password: [your email address]
19:26:04.300: hobbes.nmsu.edu: 220-
19:26:04.300: hobbes.nmsu.edu: 220
19:26:04.300: hobbes.nmsu.edu: USER anonymous
19:26:04.480: hobbes.nmsu.edu: 331 Please specify the password.
19:26:04.480: hobbes.nmsu.edu: PASS
19:26:04.660: hobbes.nmsu.edu: 230 Login successful.
19:26:04.660: hobbes.nmsu.edu: SYST
19:26:04.830: hobbes.nmsu.edu: 215 UNIX Type: L8
19:26:04.830: hobbes.nmsu.edu: CWD /pub
19:26:05.00: hobbes.nmsu.edu: 250 Directory successfully changed.
19:26:05.00: hobbes.nmsu.edu: PWD
19:26:05.400: hobbes.nmsu.edu: 257 "/pub"
19:26:05.400: hobbes.nmsu.edu: CWD /pub
19:26:05.580: hobbes.nmsu.edu: 250 Directory successfully changed.
19:26:05.580: hobbes.nmsu.edu: PASV
19:26:05.750: hobbes.nmsu.edu: 227 Entering Passive Mode (128,123,88,139,171,143)
19:26:05.970: hobbes.nmsu.edu: LIST -a
19:26:06.140: hobbes.nmsu.edu: 150 Here comes the directory listing.
19:26:06.360: hobbes.nmsu.edu: 226 Directory send OK.
19:26:11.800: hobbes.nmsu.edu: CWD /pub/incoming
19:26:11.980: hobbes.nmsu.edu: 250-New uploads which have not yet been catalogued go into here.
19:26:11.980: hobbes.nmsu.edu: 250-
19:26:11.980: hobbes.nmsu.edu: 250-Please read the uploading policy (./README.POLICY or /uploadpolicy.html)
19:26:11.980: hobbes.nmsu.edu: 250-before you upload any files. Also, always be sure to get a copy of the
19:26:11.980: hobbes.nmsu.edu: 250-most recent README.TEMPLATE for your .txt file.
19:26:11.980: hobbes.nmsu.edu: 250-
19:26:11.980: hobbes.nmsu.edu: 250-*** READ AND UNDERSTAND THE ABOVE BEFORE YOU UPLOAD ANYTHING HERE. ***
19:26:11.980: hobbes.nmsu.edu: 250-
19:26:11.980: hobbes.nmsu.edu: 250-I show no pity to those who cannot follow instructions. Also, no abuse
19:26:11.980: hobbes.nmsu.edu: 250-will be tolerated. Abusing things only hurts everyone. If you don't
19:26:11.980: hobbes.nmsu.edu: 250-understand that, then you don't belong here!
19:26:11.980: hobbes.nmsu.edu: 250-
19:26:11.980: hobbes.nmsu.edu: 250 Directory successfully changed.
19:26:11.980: hobbes.nmsu.edu: CWD /pub/incoming
19:26:12.200: hobbes.nmsu.edu: 250 Directory successfully changed.
19:26:12.240: hobbes.nmsu.edu: CWD /pub/incoming
19:26:12.440: hobbes.nmsu.edu: 250 Directory successfully changed.
19:26:12.440: hobbes.nmsu.edu: PASV
19:26:12.760: hobbes.nmsu.edu: 227 Entering Passive Mode (1xxxxxxx 5)
19:26:12.940: hobbes.nmsu.edu: LIST -a
19:26:13.110: hobbes.nmsu.edu: 150 Here comes the directory listing.
19:26:13.290: hobbes.nmsu.edu: 226 Directory send OK.
I also increased the timeout from 5 seconds to 9 cause it takes very long until hobbes responded.