got the same problem here in france, i asked to nanopool support and they gave me direct ip adresses of eu pool and it works but i dont know why...
it looks like dns problem because ip adress works but eth-eu1.nanopool.org does not work anymore for me....
i have the same problem on over pools like ethermine.
it looks like provider problem who cannot retrieve correct ip adress.
somebody to help solve this tricky problem