I have an Archos Xenon 101 v2 (from the "About tablet", "Model number" in the "Settings" area and app.
I also have a Talktalk WiFi router, the one supplied with the TV package. It is actually a Huawei HG533
I have a problem like this, the Internet disconnects after a random period of time. The WiFi and connected indicators remain for a long time after but they do eventually disappear. The tablet has to be restarted before Internet can be restored which for an Android tablet is a joke I can't get any work done. At the same time no other devices suffer disconnection and the router remains actively connected to the Internet and stable.
I tested the tablet in Spain with another router, a TP-LINK model TL-WR841N, 300Mbps N-Type WiFi with WPS this was supplied byy the broadband company that delivered broadband through the TV aerial, wow! Everything was excellent, stable.
I returned home and bought a £25 Huawei WS550, 450Mbps dual core processor, N-Type WiFi with WPS but no Broadband modem. It was so easy to install as it auto-negotiated everything and now my tablet runs a WiFi Internet connection perfectly and is stable.
The issue is the hardware driver provided by ARCHOS. It is specific to the N-Type WiFi chipset they have chosen for this generation of tablet. The bit I find interesting is the Amazon Prime app, when this was run it replaced the hardware driver, ie. at a very low level to prevent copyright infringement of their video streaming service. This confirmed the location of the problem. As long as the same chipset and driver is in use the problem will continue to exist with ARCHOS tablets being unstable with one or more WiFI routers.
I am still negotiating with ARCHOS as my tablet has been replaced several times without the problem being fixed. ARCHOS argue a warranty period of 1 year. In the UK consumer law provides a warranty period of 6 years. I advise you keep your receipts and not give up if you experience this problem with your tablet. It is basically faulty, ARCHOS had to write their own device drivers for their own device hardware choices. That work is not done for them by Android, ignore what tech people say on this, apparently the only company who have had this done for them recently is Google themselves with the Nexus range of mobile devices. I suggest you argue the tablet "Is not fit for the purpose for which it was sold". My original tablet was a Platinum 97 HD. It developed a fault and ARCHOS replaced it without asking my permission first. They replaced my property with the Xenon 101 v2 and this is NOT HD. I cannot watch HD or even pass it forward to an HD screen via HDMI because the digital download is automatically reduced to SD because the 'local device' is not HD. Pursue your rights, do not be fooled by a "tech person" who just wants to go for lunch! Demand your issue is escalated to a manger. Continue to do this until you meet someone with knowledge of your rights. You have a right for this to be done too. Do not give in to being bullied, do research into your problem and be reassured by your research. Consumer law in the UK is surprisingly strong taking out a case in the small claims court is easy too. Historically this is because there were many deaths during the industrial revolution and the 1800's due to adulterated food and bogus health claims for many poisonous compounds. Materials science didn't get started until the same period and that was the foundation of Health & Safety. A bit of off topic text never hurt anybody as far as I know?
Thanks for your time if you have read this. I find tech support can be a bunch of

's if you are not careful. Fortunately not everybody.