GUIMiner - "connecting"

[Gremlin57]

I have 4 mining pc's, all running win7 64 bit and 2 R9 290 cards each.
Im mining on Slushi'spool.
2 run really well, steady stable no connection issues.
2 continually have connection issues.
When trying 2 solve the connectivity issues I noticed that the proxy was showing very high pings, often over 500ms.

All go through the same router. Have changed lan cables. with no change.

Any help would be very much appreciated.

[Gator-hex]

Why are you using a proxy? To hide your IP? If it's not in your control not a lot you can do about that other than try another proxy.
One more local would have a lower ping.

Anyway, just in case it's a local issue try this..
Make sure the CPU isn't running 100% (maybe a mining virus) and make sure all have different IP addresses.

Sometime the UTP connectors fill with dust if not been used for some time. Try cleaning then with a cotton bud or compressed air or something.
If it's damp where you live (steamy windows) they may even be rusty, take a small piece of sandpaper too them.

Maybe there is a shortage IRQ addresses. Not very common these days, but go into the BIOS and turn everything off that's not needed.

If that don't work, maybe it's a bad network card or an old slow one on the motherboard, try using a new network card in a slot or USB.