Hi,
thanks for reaction, the net is simple 192.168.1.0/24 without subnets and without VLANs. I didn't see any timeouts (ping cont.) during dropouts. Even I expect that DNS don't play a role in it.
VCSA in ESXi 192.168.1.147
ESXi1 192.168.1.130/1 (second one is VMkernel)
ESX2 192.168.1.135/6
VIC 192.168.1.101, that's all.
Petr