Another update on this... Just installed and tried Solr 8.8.2 (this is the latest version supported by Sitecore)
All works fine with Java 11 and SSL So something has been updated between 8.1.1 and 8.8.2 that fixes the Java 11 SSL connectivity... I still suspect Jetty version - this is 9.4.34 in Solr 8.8.2 as opposed to 9.4.14 in Solr 8.1.1 Can anyone give me pointers to updating the jetty version on Solr 8.1.1? Is it just a case of overwriting the jetty jars in dist? Ta! Paul