Cisco Routers :: Linksys SRW2008P Decreases Network Speed

I try to connect Siemens SIP IP phone to switch LinksysSRW2008P with PoE for scheme:
main switch <-------> linksys <-------> phone

I can't have access to Linksys by local network or web interface, so I connect through COM port and reboot the device and restore all settings to defaults. There was another linksys switch with the same default IP in my network, so I've tried to change ip address for my Linksys device. After that I can ping switch IP without lost packages successfully and partly access to login page by web, but including Linksys to the local network causes decreasing all network working speed, so the web administrative form can not be loading at all.    In both cases (default ip or another one) the set isn't working, so I can't have access to the phone by ping or web interface. The cable to main switch inserts to port 1 and green rectangle indicator is flashing rapidly. The cable to the phone inserts to port 2 and orange indicator is lighting, green indicator is flashing slowly.   Interestingly, only one port has status UP (port 1), all another port has status DOWN. If I replace cables ports with each other, only the port where cable to main switch is inserted, will have status UP. The phone station is getting power from switch in both cases.  I've tried to change Spd/Dpx ports' parameters, used DHCP for getting IP, but I've gotten no result.  How can I solve the problem? Is Linksys switch worked or defective?