iCloud requests fail with timeout after a few minutes of connectivity
Maybe it is an DNS problem. 
Could you check if the resolution of host p29-quota.icloud.com works with your DNS server?

admin:~$ host p29-quota.icloud.com
p29-quota.icloud.com is an alias for p29-quota.fe.apple-dns.net.
p29-quota.fe.apple-dns.net has address 17.248.147.21
p29-quota.fe.apple-dns.net has address 17.248.147.19


If not try a differnet DNS server like google: 8.8.8.8