From thread:
Each time I turn on the DSL modem DSL sync is becoming more difficult. Today I had to try about 10 times. The DSL modem loses sync frequently. I have 2 DSL modems as noted below, and the issue happens with both. Performed the usual tests, including AT&T standard internet telephone line test which showed successful. Because of the testing I've done, I don't think the issue is on my end.
I checked the stats, for a low upstream attenuation this line sure was struggling to stay in sync. Like it was overly resistive or something. I couldn't really put my finger on it, but resistive is where I was leaning.
DN CURNMR 7.5 Marginal
UP CURNMR 20.2 Good
DN ATEN 40.3 Good
UP ATEN 20.8 Good
DN RELCAP 93 Poor
UP RELCAP 57 Good
DN CURBR 2464
UP CURBR 512
DN MABR 2624
UP MABR 896
PROFNM XADSL1_9dB_HIGH_MAX_NMR
STATUS IS-NR
CODE INTERLEAVED
From end user:
I am sorry that I didn't catch the issue with the number of microfilters. We have a star topography and I had changed some of the interior wiring. Since the phones worked, I did not associate the DSL problem with the work that I had done. When I did notice the DSL problem, all of the tests were ok; but, I didn't do the math in my head that when the 2 lines were connected there were then 8 filters combined.
Problem described: poor sync/intermittent sync/ slow sync
Problem confirmed: Too many filters-resistive local circuit. Modem was probably struggling to get through star topology wiring. This wiring scenario would have caused a bridge tap condition as well as a overly resistive phone line.
Solution:
In this case here a nid/sni splitter would be the best approach. Since the end user had 2 lines he could santion the DSL to one jack and the rest of the phone lines to another connection point. NID/SNI splitters typically correct situations like this. To the DSL modem it would look like a bridge tap but the filters in the nid/sni splitter are a bit different than the regular plug in filters. The bridge tap wouldn't have been a big deal to the modem because the phone pins on the splitter would have been resistant to the DSL signal. The bridge tap would have only maybe a few inches at best. 
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Case study: Too many filters can be just as bad!