For some reason my Boinc Manager has stopped communicating with the Boinc client so nothing is downloading. has been like this for a few days. Not sure what to check.

Check that the client is actually running (Boinc.exe) in Task Manager.
If so, the check that both boinc.exe and boincmgr.exe are allowed past your firewall.

When boinc.exe is running but boincmgr.exe cannot make contact with it, it doesn't mean nothing is downloaded and nothing is crunched. It just means you don't see it in the GUI. Boinc.exe will run perfectly fine on its own.

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Check that the client is actually running (Boinc.exe) in Task Manager.
If so, the check that both boinc.exe and boincmgr.exe are allowed past your firewall.

When boinc.exe is running but boincmgr.exe cannot make contact with it, it doesn't mean nothing is downloaded and nothing is crunched. It just means you don't see it in the GUI. Boinc.exe will run perfectly fine on its own.

You may also have to open port 31416 as well.

BOINC Manager and the BOINC Daemon communicate via http on port 31416. BOINC.exe (the daemon) acts as the server. So you have to open port 31416 to BOINC.exe inbound either on your local host or on your LAN if you want remote control. If your firewall has outbound rules, you will also have to allow BOINCmgr.exe inbound on port 31416 with the same rules about local and remote control.

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BOINC WIKI

I tried everything that was suggested here cause I had the same problem. I still couldn't get it to work so I downloaded and installed version 6.10.64 from March of last year and it's connected again :-)

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