I already solved this but wanted to share as it might help someone else save a few hours
I got a new machine and installed the latest public build of Solar2d plus latest jdk8 from oracle. If you are using ironsource mediation like I am, the downloads of resources/plugins will start failing and may start happening for other remote servers as well very soon for alot of folks. This is due to TLS 1.3 being enforced more and more on servers and the default setup on windows 10 with base install does not support it.
I was able to get around it by enabling TLS 1.3 in internet explorer advanced settings under internet options, also adding the following 2 lines to my gradle.properties file for gradle 6.8.3
systemProp.https.protocols=TLSv1.3,TLSv1.2
systemProp.jdk.tls.client.protocols=TLSv1.3,TLSv1.2
Errors I was getting were of the form:
The server may not support the client’s requested TLS protocol versions: (TLSv1.3). You may need to configure the client to allow other protocols to be used. See: Build Environment
12:56:30.199 > No appropriate protocol (protocol is disabled or cipher suites are inappropriate)
SSL handshake failed
> Could not get resource ‘https://android-sdk.is.com/com/ironsource/adapters/admobadapter/4.3.23/admobadapter-4.3.23.aar’.
12:51:13.549 > Could not GET ‘https://android-sdk.is.com/com/ironsource/adapters/admobadapter/4.3.23/admobadapter-4.3.23.aar’.
12:51:13.549 > The server may not support the client’s requested TLS protocol versions: (TLSv1.3, TLSv1.2). You may need to configure the client to allow other protocols to be used. See: Build Environment
12:51:13.549 > Remote host terminated the handshake