how to change OCAMLCURL from curl to wget?

Hi,
 

 Looks like curl is broken, or, has changed enough without telling opam/ocaml that it gives this error despite trying to set OCAMLCURL to wget.  So, how to change it in a way that works?
 

 --- begin paste ---
 venk@debian:~$ (set -x && export OCAMLCURL='wget' && echo $OCAMLCURL && opam update -v && opam upgrade -v)
 + export OCAMLCURL=wget
 + OCAMLCURL=wget
 + echo wget
 wget
 + opam update -v
 default    Downloading https://opam.ocaml.org/urls.txt
   % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                  Dload  Upload   Total   Spent    Left  Speed
   0     0    0     0    0     0      0      0 --:--:--  0:00:05 --:--:--     0curl: (7) Failed to connect to opam.ocaml.org port 443: Network is unreachable
 000
 [ERROR] Skipping https://opam.ocaml.org as the repository is not available.
 

 Updating ~/.opam/repo/compiler-index ...
 Updating ~/.opam/compilers/ ...
 Updating ~/.opam/repo/package-index ...
 Updating ~/.opam/packages/ ...
 Updating the cache of metadata (~/.opam/state.cache) ...
 Everything is up-to-date.
 + opam upgrade -v
 
 Already up-to-date.
 --- end paste ---
 

 update && upgrade has been failing every time in the recent weeks so following a thread here, I removed ~/.opam and did opam init.  Now utop is gone too.  opam install utop returns 'ERROR: utop is not a valid versioned package name'.  How to get it back?
 

 Thanks in advance.