[CONFSERVER-29536] Icons on Confluence Top Navigation Bar Rendered as Letters in Internet Explorer & Firefox

Launch Internet Explorer
Navigate to Internet Options >> Security
Do the following for all zones:
1. Click Custom Level...
2. In the resulting Security Settings prompt, look for the Downloads section, and set Font download to Disable
3. Click OK and then Apply (remember to repeat these 3 steps for all zones)
Restart the OS
Navigate to Confluence after the restart, and notice that the Confluence Top Nav Bar now looks like this:

The issue is also affecting FF browser

In Internet Explorer, navigate to Tools >> Internet Options >> Security
Do the following for all zones:
1. Click Custom level...
2. In the resulting Security Settings prompt, look for the Downloads section, and set Font download to Enable.
3. Click OK and then Apply (remember to repeat these 3 steps for all zones)
If this does not work, then there could be other reasons causing this. Best would be to try to download the font pack manually via: http://<yourConfluenceURL>/s/en_GB-1988229788/4226/d7686547091e645d7b0285207c0b86be721c74eb.1/5.0/_/download/resources/com.atlassian.auiplugin:aui-experimental-iconfont/atlassian-icons.ttf to see if indeed, Confluence is serving that font pack correctly.
Customers running Confluence in SSL will need to add the following to <CONFLUENCE_INSTALLATION>/conf/server.xml (within the <Context ... /> element):
```
<Valve className="org.apache.catalina.authenticator.NonLoginAuthenticator"
       disableProxyCaching="true" securePagesWithPragma="false" />
```
After that, restart Confluence. Thanks to kevin.hughes for this suggestion

is duplicated by

CONFSERVER-30570 Confluence -- Help >> Admin >> Notifications Menu

CONFSERVER-45702 Windows 10 - IE 11 - Confluence does not render navigation bar icons

relates to

CONFSERVER-36339 task and help icon missing on the new Confluence header

No work has yet been logged on this issue.