wget https error certificate

Hi, I am unable to use https from wget on several sites. Examples:

wget https://cdimage.trisquel.info/trisquel-images/trisquel_9.0_amd64.iso.md5
--2021-03-22 09:23:55-- https://cdimage.trisquel.info/trisquel-images/trisquel_9.0_amd64.iso.md5
Resolving cdimage.trisquel.info... 209.51.188.51, 2001:470:142:5::51
Connecting to cdimage.trisquel.info (cdimage.trisquel.info)|209.51.188.51|:443... connected.
ERROR: Could not verify the certificate of cdimage.trisquel.info, issued by "CN=R3,O=Let's Encrypt,C=US":
Unable to verify issuer authority locally.
To connect to cdimage.trisquel.info insecurely, use "--no-check-certificate".

or

wget https://freedombone.net/downloads/freedombone_public_key.txt
--2021-03-22 09:28:19-- https://freedombone.net/downloads/freedombone_public_key.txt
Resolving freedombone.net... 109.150.1.218
Connecting to freedombone.net (freedombone.net)|109.150.1.218|:443... connected.
ERROR: Unable to verify freedombone.net's certificate, issued by "CN=R3,O=Let's Encrypt,C=US":
The authority of the issuer could not be verified locally.
To connect to freedombone.net insecurely, use "--no-check-certificate".

or a program that measures the upload and download speed of my ISP

$ speedtest-cli
Retrieving speedtest.net configuration...
Cannot retrieve speedtest configuration
ERROR:

Any ideas?
thanks