SSL handshake keeps failing even after adding certificates to local truststore

When executing

wget 

I have this error:

--2020-06-03 20:55:06--
Resolving docs.conda.io (docs.conda.io)... 104.31.71.166, 104.31.70.166, 172.67.149.185, ...
Connecting to docs.conda.io (docs.conda.io)|104.31.71.166|:443... connected.
ERROR: cannot verify docs.conda.io's certificate, issued by ‘CN=SSL-SG1-GFRPA2,OU=Operations,O=Cloud Services,C=US’: Unable to locally verify the issuer's authority.
To connect to docs.conda.io insecurely, use `--no-check-certificate'.

The certificates chain in the URL above contains 4 certificates.

What I have tried to solve this problem:

0) Extract the 4 certificates in the chain, from chrome when opening the url

1) Just to ensure not missing certificates, I put all the 4 certificates (namely conda1.crt, conda2.crt, conda3.crt, conda4.crt) in /usr/share/ca-certificates/mozilla/ by doing sudo cp conda*.crt /usr/share/ca-certificates/mozilla/

2) sudo vi /etc/ca-certificates.conf and append mozilla/conda1.crt, mozilla/conda2.crt, mozilla/conda3.crt, mozilla/conda4.crt at the end

3) run sudo update-ca-certificates -f

4) I can see symbolic link created under /etc/ssl/certs which looks like: conda1.pem -> /usr/share/ca-certificates/mozilla/conda1.crt, conda2.pem -> /usr/share/ca-certificates/mozilla/conda2.crt, etc.

Verification:

openssl verify -no-CAfile -no-CApath -partial_chain -CAfile conda1.pem conda2.pem
conda2.pem: OK
openssl verify -no-CAfile -no-CApath -partial_chain -CAfile conda2.pem conda3.pem
conda3.pem: OK
openssl verify -no-CAfile -no-CApath -partial_chain -CAfile conda3.pem conda4.pem
conda4.pem: OK

Result: still fail with wget

P.S.I am facing this ssl problem in many aspects and many urls since a month ago (no problem before):

1. I cannot do conda search a_package
2. I cannot do requests.get(url) in python code
3. I cannot open it in a browser within my ubuntu system (can only access in windows)
4. I cannot do fromUrl in scala

It seems the problem is not only due to one or two certificates, instead, it's a systematic problem in my ubuntu system. Looks like it's missing a list of certificates in my truststore.

uname => Linux user 5.3.0-53-generic #47~18.04.1-Ubuntu SMP Thu May 7 13:10:50 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

I'm using Oracle VirtualBox.

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