[CentOS] Kernel 2.6.32-358 networking issues...

Hi,

after a long general power failure, I had to power off/on my 

soon to be 6.4 firewall (updated to 6.4, but not rebooted yet).
After the off/on, everything seemed to be fine.
But I realized there were some specific/weird heavy slow downs.
In one case, the windows clients *uploads* would stall (very slow), 

while the linux clients had no apparent upload issues... (MTU?).
In another case, the openvpn clients could not use the connection at all 

(way too slowwww).
After trying countless of diagnostics/tests, I reinstalled/booted the old 
kernel 2.6.32-279.22.1 and... everything went back to normal.
So, for now, I am stuck with the old kernel...

Anyone else bumped into such issues after 6.4?
Setup: C6 x86_64 / shorewall+openvpn(udp)...

Thx,
JD