High Latency to Mikrotik when LAN connected

Hi there.

I am relatively new to the world of mikrotik, and RouterOs, but have been working with both for about a year now.

The network i am running comprises of about 60 pc’s connected to hubs, run by one server which does dhcp, and so forth.

I have a wireless link to a large WAN running alongside the network. I am the only one who has access to the WAN.

The problem i am having is that when i am connected to my routerboard, and have unplugged the cable to the LAN, then my latency to the routerboard is perfect, and i have no packet loss. When i connect the LAN up to my hub, the network goes haywire. After about 2 hours of connection, my latency to my routerboard rises from 0.3 ms to 180-760 ms. I don’t know what is the matter, and i assume it could be a really trivial issue.

I would appreciate any advice possible.

Many thanks

Perhaps it is possible to put normal switch instead of hub. Probably there is too much traffic on hub after two hours, that’s why ping time increases.