ERR_CONNECTION_REFUSED errors when using PBRS

Hello,

We have been using the older version of PowerBI report server for about 6 months now in the company.

Recently we started getting getting ERR_CONNECTION_REFUSED when trying to view dashboards through browser.

In september we updated PBRS from Jan2023 (or Sep2022, not sure) release to May2023 release. Before updating, any user were able to connect without any special network access, as long as it is in the domain.

Q1: Anyone experienced this, I don't know where to look to troubleshoot this issue? I can't figure out if it's configuration issue or something else.

Q2:Does service account type affect this?

TIA