[CLOSED] CDJ2000, Pro Link not working due to interference?

Hi guys, wondering if anyone can help with a technical issue. I'm running two CDJ 2000s, connected by a LAN cable to use the Link function, sourcing music from a USB hard drive. They're running into a DJM 800 mixer via the digital line in. I've used this set up in several venues and at home, and it works perfectly. However I'm having a particular problem in one venue - I set up as normal and the Link function stops working after 20 seconds or so. This has happened both times I've played there - with different LAN cables and different USB sources. The only cause I could think of was some kind of interference from somewhere. The venue has the standard amps, crossovers and a rolec system in the DJ box, as well as light controllers etc. 

I know we've got some Pioneer experts here, can anyone think of what could be causing this issue? (There is no problem with the network ports on the CDJs, no problem with the HDD or the cables before I took them to the venue.)