Lync is not working optimally via telework portal. Is this correct?

Unfortunately, this is true.
Lync demands a lot of the connection and that is reflected in disturbances in both picture and sound.
When you hear an echo to the sound, connect a headset or headphones and then that issue is resolved.
With video there can be a delay sometimes, and this is not soluble.

Always check if you have the latest client software installed. This software does not auto update itself, therefore it is important to check flequently if any updates are available. Check the following site: Receiver.citrix.com