Problem with updating snaps

Hi
I'm using UM in our office. there is a problem with snaps here. Snap can not connect to snap store. Here the error:

error: unable to contact snap store

As far as I know, our network does not use any proxy but obviously there is something in our network configuration that prevent snap from accessing snap store. As result I can't update default snap packages in UM and I think this will cause further problems with upgrading my system to 21.10.
Here is the results of curl -D- -v https://api.snapcraft.io command

    *   Trying 91.189.92.41:443...
* Connected to api.snapcraft.io (91.189.92.41) port 443 (#0)
* ALPN, offering h2
* ALPN, offering http/1.1
* successfully set certificate verify locations:
*  CAfile: /etc/ssl/certs/ca-certificates.crt
*  CApath: /etc/ssl/certs
* TLSv1.3 (OUT), TLS handshake, Client hello (1):
* TLSv1.3 (IN), TLS handshake, Server hello (2):
* TLSv1.2 (IN), TLS handshake, Certificate (11):
* TLSv1.2 (IN), TLS handshake, Server key exchange (12):
* TLSv1.2 (IN), TLS handshake, Server finished (14):
* TLSv1.2 (OUT), TLS handshake, Client key exchange (16):
* TLSv1.2 (OUT), TLS change cipher, Change cipher spec (1):
* TLSv1.2 (OUT), TLS handshake, Finished (20):
* TLSv1.2 (IN), TLS handshake, Finished (20):
* SSL connection using TLSv1.2 / ECDHE-RSA-AES128-GCM-SHA256
* ALPN, server did not agree to a protocol
* Server certificate:
*  subject: CN=api.snapcraft.io
*  start date: May  3 13:51:43 2021 GMT
*  expire date: Aug  1 13:51:43 2021 GMT
*  subjectAltName: host "api.snapcraft.io" matched cert's "api.snapcraft.io"
*  issuer: C=US; O=Let's Encrypt; CN=R3
*  SSL certificate verify ok.
> GET / HTTP/1.1
> Host: api.snapcraft.io
> User-Agent: curl/7.74.0
> Accept: */*
> 
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
HTTP/1.1 200 OK
< Server: gunicorn/19.7.1
Server: gunicorn/19.7.1
< Date: Wed, 23 Jun 2021 07:45:09 GMT
Date: Wed, 23 Jun 2021 07:45:09 GMT
< Content-Type: text/html; charset=utf-8
Content-Type: text/html; charset=utf-8
< Content-Length: 64
Content-Length: 64
< Snap-Store-Version: 39
Snap-Store-Version: 39
< X-View-Name: snapdevicegw.webapi.root
X-View-Name: snapdevicegw.webapi.root
< X-VCS-Revision: dd4c5232
X-VCS-Revision: dd4c5232
< X-Request-Id: 2D549D02AB680A325D7301BB60D2E6802BA92DE
X-Request-Id: 2D549D02AB680A325D7301BB60D2E6802BA92DE

< 
snapcraft.io store API service - Copyright 2018-2019 Canonical.
* Connection #0 to host api.snapcraft.io left intact

thank you in advance and sorry for my english.

Please try using the Software Updater as it will update any snaps you have on your system.

doesn't Software Updater need to connect snap store?

Try the Software Updater @travis82


This might help you. It gives you the commands for upgrading snaps.