the only change was the following in the web config:
This is tested using DNNFriendlyUrl provider.
after this changed we found that all broken links from various modules worked again. This was based on DNN 7.1.2
<friendlyUrl defaultProvider="DNNFriendlyUrl">
<providers>
<clear />
<add name="DNNFriendlyUrl" type="DotNetNuke.Services.Url.FriendlyUrl.DNNFriendlyUrlProvider, DotNetNuke.HttpModules" includePageName="true" regexMatch="[^a-zA-Z0-9 _-]" urlFormat="humanfriendly" />
</providers>
</friendlyUrl>
that is to change urlFormat from "advanced" to "HumanFriendly"This is tested using DNNFriendlyUrl provider.
after this changed we found that all broken links from various modules worked again. This was based on DNN 7.1.2