Boot over HTTP hang frequently on TC HP t5630w

[theovich]

Hello,
when booting TC HP t5630w
(01:00.0 Ethernet controller [0200]: VIA Technologies, Inc. VT6120/VT6121/VT6122 Gigabit Ethernet Adapter [1106:3119] (rev 82))
over HTTP, TC frequently hang when downloads vmlinuz/initrd.img
When debug is enabled "DEBUG=httpblock:3,http:3,httpconn:3,httpcore:3,tcp:3"
TC hangs every time.
LogFile

I also see link http://ipxe.org/7f826106 in console output and
with "DEBUG=undinet" these errors appear on screen console printscreens


What can I do to make it work?

Thank you for your help.
Theo