Internet slowdowns -- seem to be caused by modem or router

Hello. This is not a Dell problem but I'm hoping my friends on the Networking Forum will have some suggestions for me.

> AT&T basic DSL (Max download speed 768 kbps, max upload 384 kbps)

> Motorola 2210 modem. This is a basic dsl modem that is normally set to PPPoE connection mode. To make a non AT&T-provided router work with it requires putting the modem into Bridged Ethernet mode.

> TP-Link TL-WR541G wireless/lan router

> Netgear WNR2000v3 wireless/lan router

> Latitude E5420 laptop

> HD Fire 7 tablet

> Asus MEMO tablet

I have had this internet service for 7 years with very few problems. There are 2 of us in the house sharing it, but usually use it at different times. It's no good for streaming video but otherwise it is okay for my purposes when it is working normally.

For the last 3 years I have used the combination of the modem in bridged mode and the TP-Link router, without issues. Then in early June my phone line went dead for two days. An AT&T repairman fixed it. I think he said there was a bad relay (don't quote me) down the street from me. Then he came and put in a new connection terminal inside the box outside my house. Right after the repair was when my internet slowed to a crawl. It gets so slow that the AT&T speed test fails -- times out or fails the Latency test and stops testing.

Since then I have had several telephone and online chats with AT&T agents. They have fixed the speed problem each time by "re-setting" my connection. I don't know what that means exactly. The fixes usually lasted several days before slowdown recurred. A couple of times they scheduled a service call but cancelled it when the speed was fixed. One agent told me he could tell from his end that the wiring in my house was good and not causing the problem.

The last agent I talked to got me to hard reset the modem. Doing that fixed it again. Because a router will only work with the modem when it is in bridged mode, the router has to be taken out of the chain when doing a hard reset of the modem. I cannot leave the router out of the chain for very long because my daughter needs it to be able to connect her Fire tablet wirelessly. (I normally just use an ethernet cable connected to my laptop and turn off the wireless.)

So I have not been able to do very much testing without the router, but so far it looks like when the router is removed, it all works well with just the modem after a reset. But then when I bridge the modem and re-introduce the router it all slows down again. I have another router, the Netgear, that I had never used, so I reset the modem and put the Netgeat in the chain in place of the TP-Link. It worked fine for a day or so and then the slow down began again. I removed the router and reset the modem and it was instantly fixed, then put the router back in and slow down again.

It seems a big coincidence that this all started at the exact time that the telephone line was repaired, but it looks like the problem is with my gear, not AT&T. I would suspect the routers except that it seems unlikely that 2 different brands would have the same problem. Also the routers have different passwords from each other so seems unlikely that they both have been hacked.

The modem passes its self diagnostic test, although that might not mean much. When I hard reset the modem and it fixes the slowdown, I can't tell if the fix is due to the reset or the removal of the router, which has to be done when performing the reset. I wish I could leave the router out of the chain for a week or so and just test the modem alone, but that is not practical. Is it possible that something has failed in the modem that would let it be fine alone but cause slowdowns when linked with a router?
I don't want to buy a new modem at this time unless I have to, because one of the agents told me that AT&T will be discontinuing the dsl service in my area within a year and force me into U-verse, for which a dsl modem would be useless.