Vodafone Suresignal with Plusnet Thomson TG585 router

[#1]

Hello,
I had a Vodafone Suresignal for 2 years and in March 2015 the Suresignal power failed and never  recovered.
I had a replacement device sent by Vodafone and when it arrived I plugged it in, did the set up and was all working splendidly.
On Thurs 28th May 15,  the Vodafone Suresignal device started flashing various lights and since then goes in a continual loop trying to find a signal from the router but not connecting to the internet.
I've been back and forth between Vodafone and Plusnet and quite frankly getting very hacked off. Vodafone have asked me to check what ports on my router are being forwarded and I am no techie. They say my ISP should be able to tell me what ports are being forwarded but Plusnet saying they are not trained to do this and pointed me towards a website called portforward.com which is just as confusing as the guides they publish do not reflect the version  of router that Plusnet supply.
I work from home and use a company Blackberry also have a Vodafone iphone - neither of which work properly without the Suresignal as I am in a poor Vodafone mobile signal area so the 3G boost via the router is essential. Otherwise I get poor quality voice calls, mobile calls get cut off mid way through meetings, colleagues can't reach me as inbound calls go to voicemail even though I am not on a call etc etc so it's very important to me that the Vodafone Suresignal works.
The ports were clearly forwarding Ok prior to Thurs 28th May but what puzzles me is what has changed and why? The router dropped out around 7am and again at 2pm on this date (which Plusnet confirmed to me they could see but cannot explain why this happened). Vodafone have tried remote synching the device but this does not re-store service although Vodafone suggest it was around 1pm on 27th May that connectivity was last seen. The router dropping out is a regular occurrence as you will see if you check your logs and again Plusnet cannot explain why nor do you do anything to try and stop it from happening...."it hasn't happened for a few days so everything must be Ok now" without any root cause or 'fix' being applied.
Please, please, please can someone at Plusnet help (and provide plain English updates please/guidance)
a) for the Vodafone suresignal connectivity
b) for the continual router drop outs/connection losses.
Thanks
David

[#2]

Quote

Vodafone have asked me to check what ports on my router are being forwarded and I am no techie.

You don't need any ports forwarded , they're just fobbing you off.

Quote

The ports were clearly forwarding Ok prior to Thurs 28th May but what puzzles me is what has changed and why? The router dropped out around 7am and again at 2pm on this date (which Plusnet confirmed to me they could see but cannot explain why this happened).

Unless you explicitly did some port forwarding (which sounds unlikely) then the router dropping out on that day is probably significant. Each time your router re-establishes the connecvtion o PlusNet you MAY be assigned a different public IP address. It's been suggested in the past(but not confimed) that this change of IP can upset the Suresignal. The suggested fix is to factory reset the Suresignal and plug it back in.
Aside from the Suresignal problem, If your router is dropping the connection regularly you need to raise a fault with PlusNet.

[#3]

thanks Mr W.
You are correct no port forwarding had or has taken place prior to or since the failure of the Suresignal.
I have reported the router dropping to PlusNet several times. Each time Plusnet say they can see the router has dropped and acknowledge it but because it is intermittent, no root cause has been established they just say it's no longer an issue and take no further action. Normally this is followed by an email saying that the issue must be linked to my wireless connection to/from my laptop which I keep saying is hardwired via an ethernet cable to the router so please don't use the wireless connection as the excuse.
Feel like I am going round in a loop TBH.
I followed the factory reset for the Suresignal over last few days and again tonight and it's made no difference.
Anymore suggestions?
Dave

[#4]

Just a thought, the plusnet broadband firewall hasn't got accidently turned on in the portal?
I had some sure signal problems a couple months back which turned out to be my router failing which I was able to test by using a sure signal I use in another location which also wouldnt work on the connection, yet both would work on a different connection I had access to.