I too am getting "Pool Connection Lost" errors on Mine77
ports 7777 and 7788
Which miner? I still get them if I use xmr-stak-amd (tried it on 4 different rigs and all available ports) but sgminer-gm-nh works fine on port 7777. Weird as I'd been using xmr-stak-amd for a couple of days with no problems until the pool daemon was restarted earlier today.
I am using stak's miner as well, the Nvidia version.
It was working perfectly before. My errors also began after the daemon's restart on the pool.
Not familiar with the Nvidia version, but I assume you have the same options. Try turning TLS off and using port 8888 or 7777.